Compositions and methods for treating autoimmune and inflammatory disorders

ABSTRACT

Ligand-specific HVEM variants, compositions comprising such variants, and methods of treating inflammatory diseases comprising administering such variants, are provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit of priority of U.S. Utility patent application Ser. No. 13/677,703, now pending, which claims benefit of priority under 35 U.S.C. § 119(e) of U.S. Ser. No. 61/597,634, filed Feb. 10, 2012; and U.S. Ser. No. 61/560,081, filed Nov. 15, 2011, the entire contents of which are incorporated herein by reference in their entireties.

STATEMENT OF GOVERNMENT RIGHTS

This invention was made in part with Government support under National Institutes of Health grants AI067890 and AI033068. The Government has certain rights to the invention.

BACKGROUND Field of Invention

The present invention relates generally to biotherapeutics directed at the inhibitory co-signaling receptor, BTLA and more specifically to therapeutic indications including autoimmune and inflammatory disorders.

Background Information

In healthy individuals the natural inflammatory response to infections and cancer is tightly regulated by a number of positive and negative control mechanisms on multiple cell lineages. This regulation can at times be co-opted by specific infectious agents or when specific pathways are compromised by somatic mutations leading to diseases of inflammatory pathogenesis. Activation of TNFRSF14 (Herpesvirus entry mediator, -HVEM) within various tissues by its ligands LIGHT (TNFSF14), BTLA (B and T Lymphocyte Attenuator), and CD160 leads to a broad range of inflammation countered by the activation of lymphocyte expressed BTLA by HVEM. CD160 shows more restricted cellular expression on natural killer cells and cytotoxic T cells and was reported to also inhibit lymphocytes responses. However, it has been determined that CD160 activates positive signals in lymphocytes in response to HVEM ligation.

Tumor necrosis factor inhibitors including the decoy receptor etanercept and antibodies (eg., adalimumab) have shown significant responses in patients with autoimmune diseases. TNF inhibitors are effective in 30-40% of patients with rheumatoid arthritis and other autoimmune diseases. However, a majority of patients show a partial or no response to this class of drugs. The basis of this failure to respond to TNF inhibitors remains unexplained. The mechanism of action of the TNF inhibitors is direct blockade of TNF binding to its receptors, halting a proinflammatory pathway. The main effect of blocking TNF is to quell innate inflammatory cells, but T cells may not be impacted, and TNF blockade alone may not reestablish homeostasis. The present invention targets a specific inhibitory pathway to attenuate inflammatory pathways and pathologic immune responses.

Substantial evidence indicates that HVEM is critically important when expressed in mucosal epithelium to suppress inflammation mediated by autoreactive T cells and macrophages. In a mouse model of Crohn's Disease, the loss of TNFSF14 in epithelium dramatically accelerated the onset of intestinal inflammation; BTLA expression in T cells and innate effector cells was required to suppress inflammation. These results established the physiological relevance of the HVEM-BTLA signaling pathway between different organs. In a chronic lung inflammation model of asthma, the LIGHT-HVEM system revealed itself as an essential pathway for memory T cells that drive pathology to persist in the lung. Moreover, LIGHT-LTβR pathway drives pathologic lung remodeling. These attributes place the HVEM system in a unique position to regulate immune responses. While the use of biologic intervention to target these pathways has led to some success in controlling HVEM mediated inflammation, it has previously been difficult to discriminate tissue and cell-specific effects due to the complexity of ligand interactions and the variability in response from specific targets.

Inflammatory responses to infections and cancer are regulated by a number of positive and negative control mechanisms on multiple cell lineages. Natural killer (NK) cells are an essential component of the innate immune system that protect against a wide range of pathogens, particularly against herpesviruses. Mature NK cells express a diverse array of receptors that activate cytolysis and cytokine release. NK cell activation is balanced by an equally varied number of inhibitory receptors that prevent uncontrolled cytolysis and inflammation through the recognition of self major histocompatibility complex (MHC) molecules in healthy, uninfected cells.

Many herpesviruses have manipulated this balance in order to prevent clearance of infected cells, allowing for viral replication and the establishment of latency. In order to become fully functional effector cells receptive to activating ligands, NK cells develop and are primed in response to the cytokine IL-15, and to a lesser extent IL-2 in vivo, both of which activate common γ chain signaling. IL-2 and IL-15 also induce the expression of antiviral interferon-γ and surface lymphotoxin (LT)-αβ.

Recent studies have shown that somatic mutations in TNFRSF14 either through deletion or nonsysnonymous mutation are among the most common gene alterations in follicular and diffuse large B cell lymphoma. Follicular lymphoma harboring acquired TNFRSF14 mutations are associated with worse prognosis, highlighting the anti-inflammatory effect of HVEM in the tumor microenvironment. While the mechanism for the tumor suppressive role of HVEM is unclear, the absence of NK cell and cytotoxic T cell costimulation through CD160 may lead to aborted anti-tumor responses. Alternatively, the absence of HVEM would prevent inhibition of T cells expressing BTLA, thus promoting the release of B cell growth factors. Finally, the absence of HVEM may act in a cell intrinsic manner in tumor cells to prevent the initiation of death signals. Additionally, lymphoma bearing HVEM deletions would express BTLA alone and not in a complex with HVEM, and thus would be exposed to ligands from other cells, antibodies or biologics which could drive inhibitory signals to the tumor cell.

The HVEM (TNFRSF14) (EMBL-CDS: AAQ89238.1: Homo sapiens (human) HVEM is a member of the tumor necrosis factor receptor superfamily expressed on lymphocytes, regulates immune responses by activating both proinflammatory and inhibitory signaling pathways (alternatively, one of skill in the art can use other known HVEM sequences, such as (Genentech) or the NCBI sequence, which may differ by 1 base (e.g., a Lys to Arg change at position 16 in the signal sequence (not in the mature protein)). HVEM binds the TNF-related ligands LIGHT (TNFSF14) and LT-α, and the immunoglobulin domain containing receptors B and T lymphocyte attenuator (BTLA). BTLA activation results in phosphorylation of its cytoplasmic tyrosines and recruitment of the tyrosine phosphatases Src homology domain 2 containing phosphatase-1 (SHP1) and 2, resulting in diminished antigen receptor signaling in T cells and B cells. In contrast, CD160 both activates NK cells and acts as an inhibitory receptor on a subset of CD4⁺ T cells. In T cells, LIGHT-HVEM signaling enhances antigen induced T cell proliferation and cytokine production.

Human Cytomegalovirus (CMV), a β-herpesvirus, contains a number of genes that modulate host immune responses and specifically NK cell activation. Many of these genes are encoded within the unique long subregion (U_(L))/b′ of the CMV genome that is not essential for replication in vitro The UL144 open reading frame contained within the (U_(L))/b′ locus was first identified as an expressed transcript encoding a type 1 transmembrane protein and as an ortholog to HVEM. UL144 does not bind LIGHT or LT-α, presumably because it lacks the third and fourth cysteine-rich domains (CRD) contained in HVEM, although it does bind and activate BTLA via CRD1 to restrain T cell proliferation.

Because HVEM activates both proinflammatory and inhibitory signaling pathways, HVEM has an important role in regulating inflammation. Additional evidence supports the importance of HVEM's role. For example, HVEM plays a role in suppression of inflammation mediated by autoractive T cells and macrophages in mucosal epithelium. In a mouse model of Crohn's disease, the loss of HVEM in epithelium dramatically accelerated the onset of intestinal inflammation; BTLA expression in T cells and innate effector cells was required to suppress inflammation. In a chronic lung inflammation model of asthma, the LIGHT-HVEM system is an essential pathway for memory T cells that drive pathology in the lung. Moreover, the LIGHT-LTβR pathway drives pathologic lung remodeling and the HVEM-BTLA system can counteregulate the LTβR pathway.

A ligand-specific HVEM protein, including a ligand-specific HVEM protein that binds to BTLA but not to LIGHT or CD160, would be useful for treating inflammatory diseases and may also be useful for suppressing growth of BTLA expressing tumor cells. An HVEM specific for CD160 may provide activating signals that induce innate lymphocytes, such as NK cells, or T cells to arrest the growth or kill tumor cells.

SUMMARY

The present disclosure includes an understanding of a cytokine pathway that controls both proinflammatory and inhibitory signaling in T and B cells, antigen-presenting dendritic cells, and innate lymphoid cells, and methods of use of the same. TNFRSF14 or herpesvirus entry mediator (HVEM) serves as a molecular switch between proinflammatory and inhibitory signaling because it binds two distinct classes of ligands: LIGHT, a TNF related ligand is highly inflammatory in its membrane bound form and Lymphotoxin-α. TNFRSF14 also engages BTLA (B and T lymphocyte attenuator) an Ig superfamily member that activates inhibitory signaling, and CD160. TNFRSF14 is part of the wider TNF/lymphotoxin network (FIG. 18). This complex network of signaling pathways is defined by shared ligands and receptors. Although at first glance these pathways appear redundant, surprisingly evidence indicates that each pathway holds intrinsic regulatory function with unique biologic impact. The present disclosure provides a series of novel mutations within HVEM that show specificity for each ligand and are able to distinguish pro-inflammatory versus inhibitory responses and methods of using the same. The present invention shows that HVEM-Fc is stimulatory to activation of NK cells and that HVEM variants which bind and engage BTLA but do not bind CD160 are inhibitory to activation of NK cells.

The present disclosure is based on the discovery that the Cytomegalovirus protein UL144, which is a structural and functional mimic of HVEM, specifically selects for BTLA binding and inhibits natural killer cell activation through BTLA without binding CD160. The present invention includes methods employing the discovery that HVEM variants and UL144-Fc can be used to inhibit natural killer cell activation in a broad spectrum of inflammatory and auto-immune diseases, as well as cancer.

In one aspect, the invention provides an isolated HVEM polypeptide variant, wherein the variant binds to BTLA and does not bind to CD160. In certain embodiments, the variant does not bind to CD160, LIGHT or LTα.

In one embodiment, the HVEM polypeptide variant includes a wild-type HVEM protein (SEQ ID NO: 79) having one or more amino acid substitutions at residue position 59, 60, 61, 72, 82, 109, 232 or any combination thereof.

In certain embodiments, the HVEM polypeptide variant includes a wild-type HVEM protein with an amino acid substitution at position 109. In another embodiment, the variant includes a wild-type HVEM protein with an amino acid substitution at position 59. In another embodiments the variant includes HVEM R109W. In another embodiment the variant includes HVEM P59S. In various embodiments, the variant is a truncation of a wild-type HVEM protein which includes the extracellular domain of HVEM or a portion thereof, having one or more cysteine rich domains (CRDs). In another embodiment, the variant further includes a suitable dimerizing domain, such as IgG1 Fc.

In one embodiment, binding of the HVEM polypeptide variant to an HVEM ligand, such as BTLA, inhibits IL-2 signaling. In another embodiment, binding of the variant to an HVEM ligand, such as BTLA, reduces expression of LT-β and interferon-γ.

In another aspect, a pharmaceutical composition comprising an isolated HVEM polypeptide variant, wherein the variant binds to BTLA and does not bind to CD160, and a pharmaceutically acceptable carrier, is provided.

In another aspect, an isolated nucleic acid molecule encoding a HVEM polypeptide variant is provided.

In another aspect, an expression cassette including a nucleic acid molecule encoding a HVEM polypeptide variant is provided.

In another aspect, a host cell transformed or transfected with a nucleic acid molecule encoding a HVEM polypeptide variant is provided.

The disclosure also provides a method for treating an inflammatory or auto-immune disease in a subject. The method includes administering to a subject a pharmaceutical composition including an isolated HVEM polypeptide variant, wherein the variant binds to at least one ligand for HVEM, such as BTLA, and does not bind to at least one other ligand for HVEM, such as CD160, and a pharmaceutically acceptable carrier.

In another aspect, the disclosure provides a method of inhibiting a proinflammatory response in a subject comprising administering to the subject an agent which inhibits binding of herpesvirus entry mediator (HVEM) to CD160 or agonizes BTLA binding to HVEM. In various embodiments, the agent inhibits activation of natural killer (NK) cells and is a negative regulator of IL-2 signaling. In various embodiment, the agent is a polypeptide, antibody, or fragments thereof, UL144 or HVEM polypeptide variant as described herein. In certain embodiments, the agent specifically inhibits binding of HVEM to CD160 without inhibiting binding of HVEM to BTLA, such as UL144 or HVEM polypeptide variant as described herein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A-1C are graphical representations. FIGS. 1A and 1B show traces of levels of binding of human HVEM Fc and human CMV UL144 Fc to human BTLA Fc, respectively. FIG. 1C shows traces of levels of binding of RhCMV UL144 Fc to human BTLA Fc.

FIGS. 2A and 2B are graphical representations depicting levels of staining of HVEM Fc, human CMV UL144, or polyclonal or monoclonal antibodies specific for human BTLA of EL4 cells transduced with wild-type or mutant human BTLA FIG. 2C illustrates a 3-D structure of BTLA complexed to HVEM (top) and rotated 90° about the y-axis complexed with a second BTLA Ig molecule (bottom).

FIGS. 3A-3D are graphs depicting levels of staining with HVEM Fc (A) or human CMV UL144 Fc (B) of 293T cells transfected with BTLA alone or with HVEM or human CMV UL144, and staining with BTLA Fc of 293T cells transfected with HVEM (C) or human CMV UL144 (D) alone or with wild-type, R42D, or E57A BTLA.

FIGS. 4A and 4B are graphical representations depicting levels of staining with the indicated concentrations of HVEM-Fc (A) or human CMV UL144 Fc (B) of EL4 cells expressing human BTLA or human CD160 respectively.

FIGS. 5A-5B are graphical representations depicting specific early co-activation of CD56dim NK cells by HVEM-Fc during response to CMV. FIGS. 5A-5B illustrate the activation of human peripheral blood cell subsets measured by CD69 (A) or CD107a (B) expression during a response to CMV infected NHDF cells following treatment with control Ig, UL144-Fc or HVEM-Fc. Freshly isolated PBMC cultured with mock- or CMV-infected NHDF cells were left untreated or were treated with HVEM-Fc, UL144-Fc, or human Ig control. FIG. 5A depicts graphs which indicate the percent of cells expressing CD69 within CD3+CD8+, CD3+CD4+, CD19+, CD56dim, CD56bright, or CD14+ gates over one week of culture. FIG. 5B depicts graphs which indicate the percent of cells expressing surface CD107a within CD56dim, CD56bright, and CD3+CD8+ cells following overnight culture. Results are representative of two separate experiments with at least 4 donors each. Graphs show mean+/−SEM, significant p values are shown.

FIG. 6A-6G are graphical representations depicting NK cell costimulation by HVEM-Fc correlates with expression of CD160. FIGS. 6A-6I illustrate the relative expression of CD160, BTLA, LIGHT, or HVEM in human peripheral blood cells (A-D), and correlations of CD56dim NK cell expression levels of these proteins and NKG2C and donor CMV seropositivity with the activation of NK cells by HVEM-Fc in the in vitro CMV response. Figures A-D are graphs which show MFI of BTLA (A), CD160 (B), HVEM (C), or LIGHT (D) in PBMC gated on CD14⁺, CD19⁺, CD3⁺CD4⁺, CD3⁺CD8⁺, CD56^(dim) and CD56^(bright). Data points represent individual donors Enhancement of CD69 expression in NK cells by HVEM-Fc in FIG. 1A was calculated as the difference between CD69 expression in HVEM-Fc-treated and control-treated samples. FIGS. 6E-I are graphs showing correlations between enhanced CD69 and NK cell expression of CD160 (E), BTLA (F), LIGHT (G) and percent NKG2C⁺ (H). R² values for correlations are shown.

FIGS. 7A-7F are graphical representations depicting UL144 binding restricted to BTLA. FIGS. 7A-B. Human BTLA- or CD160-expressing EL4 cells were stained with the indicated concentrations of HVEM-Fc or human CMV UL144 Fc. EC50 values calculated using four parameter (variable slope) analysis. FIG. 7C. Cells used above were stained with 20 μg/ml of wild-type, Y61A, or K64A HVEM-Fc. FIG. 7D. Cells used above were stained with 20 μg/ml of Fiala strain human CMV, G46K, or rhesus CMV UL144-Fc. FIG. 7E. Representative human CMV group UL144- or HVEM-expressing 293T cells were stained with 50 μg/ml of BTLA-Fc (white) or CD160-Fc (black). FIG. 7F. Human or rhesus BTLA- or CD160- expressing 293T cells were stained with 20 μg/ml of HVEM-Fc, human CMV UL144-Fc, or rhesus CMV UL144-Fc. Dot plots of GFP plotted against anti-human Fc show selective loss of interaction between CD160 and human CMV UL144. * No staining.

FIGS. 8A-8B are graphical representations depicting specific co-activation of CD56^(dim) NK cells by HVEM-Fc in response to IL-2. FIGS. 8A-B are graphs showing the induction of CD69 (A) and interferon gamma (B) in CD56dim, CD56bright, and CD8+ T cells following interleukin 2 stimulation of human peripheral blood cells treated with Ig control, UL144-Fc, or HVEM-Fc. Freshly isolated PBMC were treated with HVEM-Fc, UL144-Fc, or human Ig control and stimulated with 10 or 100 U/ml of IL-2. Graphs indicate the percent of cells expressing CD69 (A) or intracellular IFN-γ (B) within CD56^(dim), CD56^(bright) and CD3⁺CD8⁺ cells following overnight culture.

FIGS. 9A-9F are graphical representations depicting HVEM-Fc co-stimulation of IFN-β and IL-2 activation of NK cells. FIGS. 9A-F are histograms (A-B), and graphs (C-D) showing the induction of CD69, CD25 and CD107a in CD56dim and CD56 bright following interferon beta or interleukin 2 stimulation of purified NK cells treated with Ig control, UL144-Fc, or HVEM-Fc. The levels of cytokines produced in the cultures of stimulated NK cells are shown in graphs (E-F). Purified CD56⁺ cells from whole blood were treated with HVEM-Fc, UL144-Fc or human Ig control and stimulated overnight with 20 U/ml of IFN-β (A, C, E) or 10 U/ml (B, D) or (F) of IL-2. Overlaid histograms of cells from a representative donor show CD56 plotted against CD69 (top row), CD25 (middle row), or CD107a (bottom row) (A-B). Graphs show the percent of CD56^(dim) cells expressing CD69 (top row) CD25 (middle row) and CD107a (bottom row) (C-D). Results are representative of two separate experiments with at least 4 donors each, mean+SEM. Culture supernatants were collected after three days of treatment and assayed for the presence of secreted cytokines (E-F). Levels of IFN-γ and IL-8 are shown for IFN-β and IL-2 stimulation, and levels of TNF-α and LT-α are shown for IL-2 stimulation. No TNF-α or LT-α was detected following IFN-β treatment, and no IL-1-β, IL-2, IL-4, IL-5, IL-6, IL-10, or IL-12 p70 was detected following either stimulation. Graphs show mean+SEM, significant p values are shown. * none detected.

FIGS. 10A-10E are graphical and pictorial representations depicting phosphorylation of STAT1 and STAT5 is regulated by HVEM-Fc and UL144-BTLA. FIGS. 10A-10B are histograms of staining of NK92 cells with antibodies to BTLA (A) or CD160 (B.). Additional western blots shows interleukin 2 stimulation of NK92 cells treated with control Ig, HVEM-Fc, or UL144-Fc treatment (C), interleukin 2 stimulation of NK92 cells treated with control Ig or anti-BTLA (D), and interferon beta stimulation of NK92 cells treated with control Ig or anti-BTLA (E). The times of the stimulation are indicated above the blots, and the proteins blotted for are shown to the right of the blots. FIGS. 10A-B. NK92 cells were stained with anti-BTLA and anti-CD160. FIGS. 10C-E. NK92 cells were treated with the indicated Fc proteins or antibodies and stimulated with either 20 U/ml IL-2 (C), 2, 20, 200 U/ml IL-2 (D), or 1, 10, 100, and 1000 U/ml IFN-β (E) for the indicated times. Western blots show whole cell extracts of phospho-JAK1, phospho-STAT5, and phospho-AKT to monitor IL-2 signaling, or phospho-STAT1 to monitor IFN-β signaling, and STAT5 and actin to control for total protein levels.

FIG. 11A-11C are pictorial representations depicting target cell activation of NK cells is regulated by HVEM and UL144. FIG. 11A-11C are western blots showing stimulation of NK92 with K562 cells treated with control Ig, HVEM-Fc, or UL144-Fc treatment (A), stimulation of NK92 with K562 cells treated with control Ig, HVEM-Fc, or HVEM R109W-Fc treatment (B), and stimulation of NK92 with K562 cells transfected with control vector or HVEM (C). The times of the stimulation are indicated above the blots, and the proteins blotted for are shown to the right of the blots. FIGS. 11A-B. NK92 cells were treated with HVEM- or UL144-Fc (A) or HVEM-Fc or HVEM R109W-Fc (B) and stimulated with Imatinib treated K562 cells for the indicated times. FIG. 11C. NK92 cells were stimulated with Imatinib treated K562 cells transduced with GFP control- or HVEM-expressing vector for the indicated times. Western blots show whole cell extracts of phospho-ERK1/2 and phospho-AKT (S473) to monitor activation and total AKT and total ERK2 to control for total protein levels. K562 cells alone are shown to show target cell specific signals.

FIG. 12 is a tabular representation of relative binding of HVEM mutants to ligands. FIG. 12 shows a summary of the binding interactions between wild-type or 10 human HVEM proteins with BTLA, CD160 and LIGHT. The region of the amino acid substitution within HVEM is shown at the right of the table. Wild-type and mutant human HVEM were compared for the binding to human BTLA, CD160, and LIGHT. Mutations tested include P59S, G60D, Y61C, G72P, T82P, Ins92I, A102P, R109W, V215D, and G232S, all identified in follicular lymphoma and diffuse large B cell lymphoma.

FIG. 13 is a series of graphical representations depicting expression of HVEM mutants is similar by antibody staining FIG. 13 is histograms of cells transfected with wild-type or mutant HVEM stained with anti-HVEM. 293 cells were transduced with wild-type or mutant HVEM, or control vector and stained with anti-HVEM, and analyzed by flow cytometry.

FIG. 14 is a series of graphical representations depicting comparison of LIGHT/CD160/BTLA binding to HVEM mutants. FIG. 14 is graphs showing the relative binding of BTLA, CD160, or LIGHT titrated onto wild-type or mutant HVEM. 293 cells were transduced with wild-type or mutant human HVEM and stained with titrated human BTLA-Fc, CD160-Fc, LIGHT-FLAG to determine the impact of mutation on ligand binding.

FIGS. 15A-D are a series of graphical representations related to BTLA binding to UL144 mutants. FIG. 15A is a graph depicting binding data of BTLA binding to UL144 mutants expressed in 293 cells. FIG. 15B illustrates a 3-D structure of UL144 showing CRD1 and CRD2 binding domains which complex with BTLA. The position of these mutations is shown in FIG. 15B, the structural representation of the UL144 protein. FIG. 15C shows the alignment of the amino acid sequence of HVEM (SEQ ID NO: 80) and UL144 (SEQ ID NO: 81) as well as the consensus sequence (SEQ ID NO: 82). FIG. 15D is a series of graphs showing the relative expression of each of these UL144 mutants using antibody staining.

FIG. 16 is the amino acid sequence of wild-type HVEM (SEQ ID NO: 79).

FIG. 17 is a diagrammatic representation of showing the domains of wild-type HVEM with amino acid position 1 corresponding to amino acid position 39 of the wild-type sequence of SEQ ID NO: 79 (the signal sequence corresponding to amino acids 1 to 38 of SEQ ID NO: 79 is cleaved in the diagram of FIG. 16).

FIG. 18 is an illustration of the HVEM Network.

DETAILED DESCRIPTION

The present disclosure is based on the discovery that a viral homolog of HVEM, the Cytomegalovirus UL144 protein, has evolved specificity for BTLA without having specificity for CD160. This discovery allows for the ligand-specific HVEM polypeptide variants to be generated that bind to BTLA, but do not bind to CD160, as well as other HVEM ligands which provides suppression and inhibition of a proinflammatory response.

Before the present compositions and methods are described, it is to be understood that this invention is not limited to particular compositions, methods, and experimental conditions described, as such compositions, methods, and conditions may vary. It is also to be understood that the terminology used herein is for purposes of describing particular embodiments only, and is not intended to be limiting, since the scope of the present invention will be limited only in the appended claims.

As used in this specification and the appended claims, the singular forms “a”, “an”, and “the” include plural references unless the context clearly dictates otherwise. Thus, for example, references to “the method” includes one or more methods, and/or steps of the type described herein which will become apparent to those persons skilled in the art upon reading this disclosure and so forth.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the invention, the preferred methods and materials are now described.

In one aspect, the present disclosure provides an isolated HVEM polypeptide variant, wherein the variant binds to HVEM ligand BTLA and does not bind to HVEM ligand CD160. In certain embodiments, the variant does not bind to HVEM ligands LIGHT or LTα.

An illustration of the HVEM Network depicting the specificity of the ligands (upper panel) and cognate receptors (lower panel) is shown in FIG. 18. The arrows define the specific ligand-receptor interaction. The TNF related ligands are shown as trimers (unboxed). LTα is secreted as a homotrimer, and has modest affinity for HVEM (dashed line). The Ig superfamily members, BTLA and CD160, and herpes simplex virus (HSV) glycoprotein D (boxed) are ligands for HVEM. Human cytomegalovirus UL144, an HVEM ortholog, binds BTLA. Decoy receptor-3 (DcR3) binds LIGHT and the paralogous ligands, Fas Ligand and TL1a.

The term “wild-type HVEM protein” or “HVEM wild-type protein” refers to the Herpesvirus entry mediator protein (HVEM) protein having the amino acid sequence disclosed in EMBL-CDS: AAQ89238.1: Homo sapiens (human) HVEM as shown in FIG. 16 (SEQ ID NO: 79).

As used herein, a polypeptide “variant” or “derivative” refers to a polypeptide that is a mutagenized form of a polypeptide or one produced through recombination but that still retains one or more desired activities, such as the ability to bind to one specific ligand, but no longer retains another activity, such as the ability to bind to a second specific ligand.

The terms “HVEM polypeptide variant” or “HVEM variant” refer to an HVEM wild-type protein whose amino acid sequence is altered by one or more amino acids, such as by mutation, substitution or truncation. The HVEM variant may have conservative changes, wherein a substituted amino acid has similar structural or chemical properties, e.g., replacement of leucine with isoleucine. The HVEM variant may have nonconservative changes, e.g., replacement of a glycine with a tryptophan. Analogous minor variations may also include amino acid deletions or insertions, or both. Guidance in determining which amino acid residues may be substituted, inserted, or deleted may be found using computer programs well known in the art, for example, DNASTAR™ software (DNASTAR Inc., Madison, Wis.). A variant of the invention will have functional properties as those with the illustrative HVEM R109W or HVEM P59S, for example.

“Isolated” or “purified” as those terms are used to refer to preparations made from biological cells or hosts means any cell extract containing the indicated DNA or protein including a crude extract of the DNA or protein of interest. For example, in the case of a protein, a purified preparation can be obtained following an individual technique or a series of preparative or biochemical techniques and the DNA or protein of interest can be present at various degrees of purity in these preparations. Particularly for proteins, the procedures may include for example, but are not limited to, ammonium sulfate fractionation, gel filtration, ion exchange change chromatography, affinity chromatography, density gradient centrifugation, electrofocusing, chromatofocusing, and electrophoresis.

A preparation of DNA or protein that is “substantially pure” or “isolated” should be understood to mean a preparation free from naturally occurring materials with which such DNA or protein is normally associated in nature. “Essentially pure” should be understood to mean a “highly” purified preparation that contains at least 95% of the DNA or protein of interest.

As used herein, the term “truncated”, “truncation” or similar terminology refers to a HVEM polypeptide variant that contains less than the full amino acid sequence of a HVEM wild-type protein having a length of 283 amino acids as shown in FIG. 16 (SEQ ID NO: 79).

The term “ligand-specific HVEM variant” refers to an HVEM variant that binds to at least one HVEM ligand and does not bind to at least one other HVEM ligand.

The term “HVEM R109W” refers to an HVEM variant that contains a tryptophan residue instead of an arginine residue at amino acid position 109 of a wild-type HVEM protein

The term “HVEM P59S” refers to an HVEM variant that contains a serine residue instead of a proline residue at amino acid position 59 of a wild-type HVEM protein.

The term “HVEM ligand” refers to a protein that binds to an HVEM wild-type and/or variant protein.

The term “UL144 protein” refers to the human cytomegalovirus UL144 protein.

The term “binds to” refers to a binding reaction that can be determinative of the presence of a protein in a heterogeneous population of proteins (e.g., a cell or tissue lysate) and other biologics. Thus, under standard conditions or assays used in binding assays, the specified polypeptide binds to a particular target molecule above background (e.g., 2×, 5×, 10× or more above background).

The term “suitable dimerization domain” includes, but is not limited to, a polypeptide domain that can associate with a second polypeptide domain to form a macromolecular complex.

The term “proinflammatory signaling pathway” refers to a biological pathway in a cell or tissue whose activation leads to an inflammatory response. In certain embodiments, a proinflammatory signaling pathway is in an immune cell or tissue. In certain embodiments, a proinflammatory signaling pathway is in a mucosal cell or tissue.

The term “inhibitory signaling pathway” refers to a biological pathway in a cell or tissue whose activation does not lead to or suppresses an inflammatory response. In certain embodiments, an inhibitory signaling pathway is in an immune cell or tissue. In certain embodiments, an inhibitory signaling pathway is in a mucosal cell or tissue.

The HVEM polypeptide variants of the present disclosure may include one or more mutations or substitutions as well as truncations as compared to wild-type HVEM protein. Reference herein to amino acid residues is made with respect to the full length HVEM wild-type protein as shown in FIG. 16 (see, also, Sequence Listing). HVEM wild-type protein includes several discrete functional domains as follows: signal peptide (residues 1-38), extracellular ligand binding domain (residues 39-202), transmembrane domain (203-223), and cytoplasmic topological domain (residues 224-283). The extracellular ligand binding domain (residues 39-202) includes four cysteine rich domains (CRDs) which define ligand specificity and are located as follows: CRD1 (residues 42-75), CRD2 (residues 78-119), CRD3 (residues 121-162) and CRD4 (residues 165-186).

It should also be recognized that reference is made herein to particular peptides beginning or ending at “about” a particular amino acid residue. The term “about” is used in this context because it is recognized that a HVEM polypeptide variant may be generated to include complete functional domains of the HVEM wild-type protein or portions thereof. Thus, a HVEM polypeptide variant may include one or a few, e.g., 2, 3 4 or 5 amino acids from the specified amino acid length. As such, reference, for example, to a HVEM polypeptide variant having an amino acid sequence of about amino acid residues 39 to 187 of SEQ ID NO: 79 would include an amino terminal peptide portion of HVEM excluding the complete signal peptide and include a carboxy terminus ending at amino acid residue 182 to amino acid residue 192, preferably at amino acid residue 187.

The HVEM polypeptide variants disclosed herein generally include all or a portion of the extracellular domain from about amino acid 39 to about amino acid 202 of SEQ ID NO: 79 and which retains BTLA binding activity but does not bind CD160. The variants may include one or more mutations or substitutions at amino acid residue position 59, 60, 61, 72, 82, 109, 232 of SEQ ID NO: 79, or any combination thereof. In various embodiments, the variant is a truncated wild-type HVEM variant having one or more mutations or substitutions at amino acid residue position 59, 60, 61, 72, 82, 109, 232 of SEQ ID NO: 79, or any combination thereof.

Truncated HVEM polypeptide variants generally include all or a portion of the extracellular ligand binding domain (residues 39-202) of HVEM wild-type protein. In various embodiments, the truncated variants may include all or a portion of CRD1; CRD1 and all or a portion of CRD2; CRD1, CDR2 and all or a portion of CRD3; CRD1, CRD2, CRD3 and all or a portion of CRD4; or alternatively all CRDs in their entireties, each of the variants having one or more mutations or substitutions. As such, in various embodiments, the variants of the present disclosure may include amino acid residues from about 39 to about 76, about 39 to about 98, about 39 to about 120, about 39 to about 141, about 39 to about 163, or about 39 to about 187 of SEQ ID NO: 79, and wherein the variant include at least one substitution or mutations and functionally retain BTLA binding activity but do not retains CD160 binding activity.

In one embodiment, the disclosure provides a HVEM polypeptide variant including CRD1 and CRD2 from about amino acid residue 39 to about residue 120 of SEQ ID NO: 79. The variant has decreased or no binding to CD160 while retaining BTLA binding, and is capable of delivering inhibitory signals to lymphocytes by avoiding activation signaling through CD160. In various embodiments, the variant further includes one or more an amino acid substitutions or mutations at residue position 59, 60, 61, 72, 82, 109 or any combination thereof. In some embodiments, the variant includes CRD1 and CRD2 from about amino acid residue 39 to about residue 120 of SEQ ID NO: 79 and further includes a mutation or substitution at either P59, R109 or both.

In one embodiment, the disclosure provides a HVEM polypeptide variant including CRD1, CRD2, and a portion of CRD3 from about amino acid residue 39 to about residue 141 of SEQ ID NO: 79. The variant has decreased or no binding to CD160 while retaining BTLA binding, and is capable of delivering inhibitory signals to lymphocytes by avoiding activation signaling through CD160. In various embodiments, the variant further includes one or more an amino acid substitutions or mutations at residue position 59, 60, 61, 72, 82, 109 or any combination thereof. In some embodiments, the variant includes CRD1, CRD2 and a portion of CRD3 from about amino acid residue 39 to about residue 141 of SEQ ID NO: 79 and further includes a mutation or substitution at either P59, R109 or both.

In various embodiments, the HVEM polypeptide variant of the present disclosure retains BTLA binding activity, but does not bind one or more of CD160, LIGHT, or LTα.

In one embodiment, the present disclosure provides an HVEM mutant R109W which has decreased or no binding to CD160 while retaining BTLA binding, and is capable of delivering inhibitory signals to lymphocytes by avoiding activation signaling through CD160.

The HVEM polypeptide variants of the present disclosure act like the viral protein in a broad spectrum of diseases, but, advantageously, without having antigenic properties of a foreign protein.

In other aspects the invention includes methods for making mutations or substitutions of HVEM used to discriminate between all of the HVEM ligands and multivalent forms of each of these HVEM variants, whereby the variants will have low antigenicity and can be used to target specific immune pathways in various diseases.

An HVEM Fc of the invention functions as a specific inhibitor of inflammatory processes and thus is used in a range of inflammatory conditions including but not limited to rheumatoid arthritis, lupus, Crohn's Disease, and similar autoimmune diseases. The present invention provides methods to expand the panel of mutant HVEM Fc proteins to create fully functional proteins capable of selectively binding either LIGHT, BTLA and CD160. TNFSF14 specific HVEM Fc blocks lung inflammation in an airway hyperresponsiveness model previously shown to be dependent on the activity of this ligand. BTLA specific HVEM Fc will be used as a broad spectrum inhibitory reagent with the capacity to inhibit T and B cell responses.

The present invention provides methods for CD160 specific HVEM to promote cytotoxic T cell and natural killer cell clearance of tumors in models of B cell lymphoma and melanoma. In several aspects of the invention, the present invention targets specific diseases in which each of the HVEM ligands has been shown to play a role. Additionally the present invention targets T cell and NK mediated immune disease in humans.

Current HVEM Fc reagents activate both positive and negative pathways by activating CD160 receptors on natural killer cells and cytotoxic T lymphocytes, and inhibitory BTLA receptors on these and other lymphocytes. The present invention provides a panel of mutated HVEM Fc reagents which can distinguish between different activating and inhibitory receptors, and methods of use of such reagents, allowing specific dampening of immune responses on these subsets where previous reagents have failed. Finally, present Fc fusion proteins are a proven technology in clinical use (Enbrel, etanercept), and while other Fc proteins target effector cytokines, the present invention provides methods to target effector cell subsets to regulate disease progression.

The present invention provides methods to identify mutations that distinguish between BTLA and CD160, and a panel of mutants that have high affinity ligand specific proteins. Another aspect of the present invention includes specific inhibition of B cells and NK cells using a viral variant of HVEM specific for BTLA. The present invention also includes activation of CD160 expressing NK cells using HVEM Fc.

The present invention provides a fusion protein of human IgG1 Fc with the cytomegalovirus protein UL144, which is specific for BTLA and which selectively activates inhibitory pathways in NK cells without activating CD160, and methods of using the same. The present invention also identifies a mutation in HVEM which selectively binds to BTLA, and a fusion protein with this mutant, and methods of using the same.

The present invention provides methods for the development of a BTLA-specific ligand constructed as a fusion protein with the ectodomain of human HVEM and Fc or other suitable dimerizing domain. The present invention provides methods for making HVEM specific mutants that, like UL144, are specific for BTLA. This molecule is significantly more efficacious at inhibiting T cell activation and innate cell activation than HVEM-Fc Modified HVEM-Fc represents a first-in-class drug as bio-modulator of inhibitory signaling.

In certain embodiments, an isolated HVEM variant, wherein the variant binds to BTLA and does not bind to CD160 is provided for. In certain embodiments, the variant does not bind to LIGHT.

In certain embodiments, the variant includes a wild-type HVEM protein or truncation thereof with an amino acid substitution at position 59, 60, 61, 72, 82, 109 and/or 232. In certain embodiments, the variant includes a wild-type HVEM protein or truncation thereof with an amino acid substitution at position 59. In certain embodiments, the variant includes a wild-type HVEM protein or truncation thereof with an amino acid substitution at position 60. In certain embodiments, the variant includes a wild-type HVEM protein or truncation thereof with an amino acid substitution at position 61. In certain embodiments, the variant includes a wild-type HVEM protein or truncation thereof with an amino acid substitution at position 72. In certain embodiments, the variant includes a wild-type HVEM protein or truncation thereof with an amino acid substitution at position 82. In certain embodiments, the variant includes a wild-type HVEM protein or truncation thereof with an amino acid substitution at position 109.

In certain embodiments, the variant includes all or a portion of the extracellular domain of HVEM-R109W. In certain embodiments, the variant includes all or a portion of the extracellular domain of HVEM-P59S. In certain embodiments, the variant includes the extracellular domain of UL144.

While the HVEM polypeptide variants of the present disclosure may be defined by exact sequence or motif sequences, one skilled in the art would understand that peptides that have similar sequences may have similar functions. Therefore, peptides having substantially the same sequence or having a sequence that is substantially identical or similar to HVEM polypeptide variants described herein are intended to be encompassed. As used herein, the term “substantially the same sequence” includes a peptide including a sequence that has at least 60+% (meaning sixty percent or more), preferably 70+%, more preferably 80+%, and most preferably 90+%, 95+%, or 98+% sequence identity with the HVEM polypeptide variant described herein which retains the same functional activity.

A further indication that two polypeptides are substantially identical is that one polypeptide is immunologically cross reactive with that of the second. Thus, a polypeptide is typically substantially identical to a second polypeptide, for example, where the two peptides differ only by conservative substitutions.

The term “conservative substitution” is used in reference to proteins or peptides to reflect amino acid substitutions that do not substantially alter the activity (for example, antimicrobial activity) of the molecule. Typically conservative amino acid substitutions involve substitution of one amino acid for another amino acid with similar chemical properties (for example, charge or hydrophobicity). The following six groups each contain amino acids that are typical conservative substitutions for one another: 1) Alanine (A), Serine (S), Threonine (T); 2) Aspartic acid (D), Glutamic acid (E); 3) Asparagine (N), Glutamine (Q); 4) Arginine (R), Lysine (K) 5) Isoleucine (I), Leucine (L), Methionine (M), Valine (V); and 6) Phenylalanine (F), Tyrosine (Y), and Tryptophan (W).

The term “amino acid” is used in its broadest sense to include naturally occurring amino acids as well as non-naturally occurring amino acids including amino acid analogs. In view of this broad definition, one skilled in the art would know that reference herein to an amino acid includes, for example, naturally occurring proteogenic (L)-amino acids, (D)-amino acids, chemically modified amino acids such as amino acid analogs, naturally occurring non-proteogenic amino acids such as norleucine, and chemically synthesized compounds having properties known in the art to be characteristic of an amino acid. As used herein, the term “proteogenic” indicates that the amino acid can be incorporated into a protein in a cell through a metabolic pathway.

The phrase “substantially identical,” in the context of two polypeptides, refers to two or more sequences or subsequences that have at least 60+%, preferably 80+%, most preferably 90-95+% amino acid residue identity, when compared and aligned for maximum correspondence, as measured using a sequence comparison algorithm or by visual inspection.

As is generally known in the art, optimal alignment of sequences for comparison can be conducted, for example, by the local homology algorithm of Smith & Waterman ((1981) Adv Appl Math 2:482), by the homology alignment algorithm of Needleman & Wunsch ((1970) J Mol Biol 48:443), by the search for similarity method of Pearson & Lipman ((1988) Proc Natl Acad Sci USA 85:2444), by computerized implementations of these algorithms by visual inspection, or other effective methods.

HVEM polypeptide variants may have modified amino acid sequences or non-naturally occurring termini modifications. Modifications to the peptide sequence can include, for example, additions, deletions or substitutions of amino acids, provided the peptide produced by such modifications retains BTLA binding activity. Additionally, the peptides can be present in the formulation with free termini or with amino-protected (such as N-protected) and/or carboxy-protected (such as C-protected) termini Protecting groups include: (a) aromatic urethane-type protecting groups which include benzyloxycarbonyl, 2-chlorobenzyloxycarbonyl, 9-fluorenylmethyloxycarbonyl, isonicotinyloxycarbonyl and 4-methoxybenzyloxycarbonyl; (b) aliphatic urethane-type protecting groups which include t-butoxycarbonyl, t-amyloxycarbonyl, isopropyloxycarbonyl, 2-(4-biphenyl)-2-propyloxycarbonyl, allyloxycarbonyl and methylsulfonylethoxycarbonyl; (c) cycloalkyl urethane-type protecting groups which include adamantyloxycarbonyl, cyclopentyloxycarbonyl, cyclohexyloxycarbonyl and isobornyloxycarbonyl; (d) acyl protecting groups or sulfonyl protecting groups. Additional protecting groups include benzyloxycarbonyl, t-butoxycarbonyl, acetyl, 2-propylpentanoyl, 4-methylpentanoyl, t-butylacetyl, 3-cyclohexylpropionyl, n-butanesulfonyl, benzylsulfonyl, 4-methylbenzenesulfonyl, 2-naphthalenesulfonyl, 3-naphthalenesulfonyl and 1-camphorsulfonyl.

In various embodiments, HVEM polypeptide variants may be administered by any suitable means, including topical, parenteral, subcutaneous, intraperitoneal, intrapulmonary, intranasal, intravenous, and/or intralesional administration in order to treat the subject. However, in exemplary embodiments, the peptides are formulated for topical application, such as in the form of a liquid, cream, gel, ointment, foam spray or the like.

In certain embodiments, the variant includes a suitable dimerizing domain. In certain embodiments, the suitable dimerizing domain is an effectorless Fc domain of an Ig, such as human IgA, IgD, IgE, IgG, or IgM. In one embodiment, the Fc domain is IgG1 effectorless Fc domain.

In certain embodiments, binding of the variant to an HVEM ligand inhibits IL-2 signaling. In certain embodiments, binding of the variant to an HVEM ligand reduces expression of LT-β and interferon-γ.

In certain embodiments, a pharmaceutical composition comprising an isolated HVEM variant, wherein the variant binds to at least one ligand for HVEM and does not bind to at least one other ligand for HVEM, and a pharmaceutically acceptable carrier, is disclosed.

In another aspect, the present disclosure provides a pharmaceutical composition comprising an isolated HVEM polypeptide variant, wherein the variant binds to BTLA and does not bind to CD160 and optionally LIGHT and LTα, and a pharmaceutically acceptable carrier.

The term “pharmaceutical agent or drug” includes a chemical compound or composition capable of inducing a desired therapeutic effect when administered to a patient or subject.

The term “patient” or “subject” as used herein refers to any individual or patient to which the subject methods are performed. Generally the subject is human, although as will be appreciated by those in the art, the subject may be an animal. Thus other animals, including mammals such as rodents (including mice, rats, hamsters and guinea pigs), cats, dogs, rabbits, farm animals including cows, horses, goats, sheep, pigs, etc., and primates (including monkeys, chimpanzees, orangutans and gorillas) are included within the definition of subject.

In certain embodiments, a pharmaceutical composition includes a therapeutically effective amount of a ligand-specific HVEM polypeptide variant as described herein and a therapeutically effective amount of at least one additional therapeutic agent including, but not limited to, at least one other anti-inflammatory therapy agent.

In certain embodiments, a pharmaceutical composition includes a therapeutically effective amount of a ligand-specific HVEM polypeptide variant as described herein and a therapeutically effective amount of at least one additional therapeutic agent including, but not limited to, at least one other anti-inflammatory therapy agent.

The disclosure also provides a method for treating an inflammatory or auto-immune disease in a subject. The method includes administering to a subject a pharmaceutical composition including an isolated HVEM polypeptide variant, wherein the variant binds to at least one ligand for HVEM, such as BTLA, and does not bind to at least one other ligand for HVEM, such as CD160, and a pharmaceutically acceptable carrier.

In certain embodiments, a pharmaceutical composition includes a pharmaceutically acceptable diluent, carrier, solubilizer, emulsifier, preservative and/or adjuvant.

In certain embodiments, a pharmaceutical composition may contain formulation materials for modifying, maintaining or preserving, for example, the pH, osmolarity, viscosity, clarity, color, isotonicity, odor, sterility, stability, rate of dissolution or release, adsorption or penetration of the composition. In certain embodiments, suitable formulation materials include, but are not limited to, amino acids (such as glycine, glutamine, asparagine, arginine or lysine); antimicrobials; antioxidants (such as ascorbic acid, sodium sulfite or sodium hydrogen-sulfite); buffers (such as borate, bicarbonate, Tris-HCl, citrates, phosphates or other organic acids); bulking agents (such as mannitol or glycine); chelating agents (such as ethylenediamine tetraacetic acid (EDTA)); complexing agents (such as caffeine, polyvinylpyrrolidone, beta-cyclodextrin or hydroxypropyl-beta-cyclodextrin); fillers; monosaccharides; disaccharides; and other carbohydrates (such as glucose, mannose or dextrins); proteins (such as serum albumin, gelatin or immunoglobulins); coloring, flavoring and diluting agents; emulsifying agents; hydrophilic polymers (such as polyvinylpyrrolidone); low molecular weight polypeptides; salt-forming counterions (such as sodium); preservatives (such as benzalkonium chloride, benzoic acid, salicylic acid, thimerosal, phenethyl alcohol, methylparaben, propylparaben, chlorhexidine, sorbic acid or hydrogen peroxide); solvents (such as glycerin, propylene glycol or polyethylene glycol); sugar alcohols (such as mannitol or sorbitol); suspending agents; surfactants or wetting agents (such as pluronics, PEG, sorbitan esters, polysorbates such as polysorbate 20, polysorbate 80, triton, tromethamine, lecithin, cholesterol, tyloxapal); stability enhancing agents (such as sucrose or sorbitol); tonicity enhancing agents (such as alkali metal halides, preferably sodium or potassium chloride, mannitol sorbitol); delivery vehicles; diluents; excipients and/or pharmaceutical adjuvants. (Remington's Pharmaceutical Sciences, 18th Edition, A. R. Gennaro, ed., Mack Publishing Company (1990).

In certain embodiments, an effective amount of a pharmaceutical composition comprising a ligand-specific HVEM variant depends on the therapeutic context and objectives. One skilled in the art will appreciate that the appropriate dosage levels for treatment will vary depending in part on the molecule delivered, the indication for which the HVEM variant is being used, the route of administration, and the size (body weight, body surface or organ size) and/or condition (the age and general health) of the patient. In certain embodiments, the clinician may titer the dosage and modify the route of administration to obtain the optimal therapeutic effect. In certain embodiments, a typical dosage may range from about 0.1 μg/kg to up to about 100 mg/kg or more, depending on the factors mentioned above. In certain embodiments, the dosage may range from 0.1 μg/kg up to about 100 mg/kg; or 1 μg/kg up to about 100 mg/kg; or 5 μg/kg up to about 100 mg/kg.

An inflammatory disease or condition includes a disease or condition that is characterized by the presence of an inflammatory response or the activation of a proinflammatory signaling pathway in a cell or tissue. In certain embodiments, a proinflammatory signaling pathway is in an immune cell or tissue. In certain embodiments, a disease is an inflammatory condition if (1) pathological findings associated with the disease or condition can be mimicked experimentally in animals by the activation of a proinflammatory signaling pathway in immune cells or tissues and/or (2) a pathology induced in experimental animal models of the disease or medical condition can be inhibited or abolished by treatment with agents that activate an inhibitory signaling pathway in immune cells or tissues.

In certain embodiments, an inflammatory disease or condition is selected from the group consisting of: rheumatoid arthritis, lupus, autoimmune diseases, Crohn's disease, ulcerative colitis, inflammatory bowel diseases, asthma, dermatitis, diverticulitis, pelvic inflammatory disease, atheroscloerosis, allergies, myopathies, and leukocyte defects. An inflammatory disease or condition may also include, but is no limited to, pruritus, skin inflammation, psoriasis, multiple sclerosis, rheumatoid arthritis, osteoarthritis, systemic lupus erythematosus, Hashimoto's thyroidis, myasthenia gravis, diabetes type I or II, asthma, inflammatory lung injury, inflammatory liver injury, inflammatory glomerular injury, atopic dermatitis, allergic contact dermatitis, irritant contact dermatitis, seborrhoeic dermatitis, Sjoegren's syndrome, keratoconjunctivitis, uveitis, inflammatory bowel disease, Crohn's disease, ulcerative colitis, an inflammatory disease of the joints, skin, or muscle, acute or chronic idiopathic inflammatory arthritis, myositis, a demyelinating disease, chronic obstructive pulmonary disease, interstitial lung disease, interstitial nephritis and chronic active hepatitis.

In another aspect, the disclosure provides a method of inhibiting a proinflammatory response in a subject comprising administering to the subject an agent which inhibits binding of herpesvirus entry mediator (HVEM) to CD160 or agonizes BTLA binding to HVEM. In various embodiments, the agent inhibits activation of natural killer (NK) cells and is a negative regulator of IL-2 signaling. In various embodiment, the agent is a polypeptide, antibody, or fragment thereof, UL144 or a HVEM polypeptide variant as described herein. In certain embodiments, the agent specifically inhibits binding of HVEM to CD160 without inhibiting binding of HVEM to BTLA, such as UL144 or a HVEM polypeptide variant as described herein.

The term “binds specifically” or “specific binding activity,” when used in reference to an antibody means that an interaction of the antibody and a particular epitope has a dissociation constant of at least about 1×10⁻⁶, generally at least about 1×10⁻⁷, usually at least about 1×10⁻⁸, and particularly at least about 1×10⁻⁹ or 1×10⁻¹⁰ or less. As such, Fab, F(ab′)₂, Fd and Fv fragments of an antibody that retain specific binding activity for an epitope of HVEM or CD160, are included within the definition of an antibody.

The term “antibody” as used herein includes naturally occurring antibodies as well as non-naturally occurring antibodies, including, for example, single chain antibodies, chimeric, bifunctional and humanized antibodies, as well as antigen-binding fragments thereof. Such non-naturally occurring antibodies can be constructed using solid phase peptide synthesis, can be produced recombinantly or can be obtained, for example, by screening combinatorial libraries consisting of variable heavy chains and variable light chains (see Huse et al., Science 246:1275-1281 (1989), which is incorporated herein by reference). These and other methods of making, for example, chimeric, humanized, CDR-grafted, single chain, and bifunctional antibodies are well known to those skilled in the art (Winter and Harris, Immunol. Today 14:243-246, 1993; Ward et al., Nature 341:544-546, 1989; Harlow and Lane, Antibodies: A laboratory manual (Cold Spring Harbor Laboratory Press, 1988); Hilyard et al., Protein Engineering: A practical approach (IRL Press 1992); Borrabeck, Antibody Engineering, 2d ed. (Oxford University Press 1995); each of which is incorporated herein by reference).

Antibodies that bind specifically with HVEM or a HVEM ligand, such as CD160 can be raised using the receptor as an immunogen and removing antibodies that crossreact. An antibody of the invention conveniently can be raised using a peptide portion of HVEM or the HVEM ligand.

The disclosure also provides a method for treating cancer in a subject. The method includes administering to a subject a pharmaceutical composition including an isolated HVEM polypeptide variant, wherein the variant binds to at least one ligand for HVEM, such as BTLA, and does not bind to at least one other ligand for HVEM, such as CD160, and a pharmaceutically acceptable carrier.

Recent studies have shown that somatic mutations in HVEM (also known as TNFRSF14) either through deletion or nonsynonymous mutation are among the most common gene alterations in follicular and diffuse large B cell lymphoma. Follicular lymphoma harboring acquired TNFRSF14 mutations are associated with worse prognosis, highlighting the anti-inflammatory effect of HVEM in the tumor microenvironment. While the mechanism for the tumor suppressive role of HVEM is unclear, the absence of NK cell and cytotoxic T cell costimulation through CD160 may lead to aborted anti-tumor responses. Alternatively, the absence of HVEM would prevent inhibition of T cells expressing BTLA, thus promoting the release of B cell growth factors. Finally, the absence of HVEM may act in a cell intrinsic manner in tumor cells to prevent the initiation of death signals. Additionally, lymphoma bearing HVEM deletions would express BTLA alone and not in a complex with HVEM, and thus would be exposed to ligands from other cells, antibodies or biologics which could drive inhibitory signals to the tumor cell.

The term “cancer” as used herein, includes a variety of cancer types which are well known in the art, including but not limited to, dysplasias, hyperplasias, solid tumors and hematopoietic cancers. Many types of cancers are known to metastasize and shed circulating tumor cells or be metastatic, for example, a secondary cancer resulting from a primary cancer that has metastasized. Additional cancers may include, but are not limited to, the following organs or systems: brain, cardiac, lung, gastrointestinal, genitourinary tract, liver, bone, nervous system, gynecological, hematologic, skin, and adrenal glands. Additional types of cancer cells include gliomas (Schwannoma, glioblastoma, astrocytoma), neuroblastoma, pheochromocytoma, paraganlioma, meningioma, adrenalcortical carcinoma, medulloblastoma, rhabdomyoscarcoma, kidney cancer, vascular cancer of various types, osteoblastic osteocarcinoma, prostate cancer, ovarian cancer, uterine leiomyomas, salivary gland cancer, choroid plexus carcinoma, mammary cancer, pancreatic cancer, colon cancer, and megakaryoblastic leukemia; and skin cancers including malignant melanoma, basal cell carcinoma, squamous cell carcinoma, Karposi's sarcoma, moles dysplastic nevi, lipoma, angioma, dermatofibroma, keloids, and psoriasis.

The following examples are provided to further illustrate the embodiments of the present invention, but are not intended to limit the scope of the invention. While they are typical of those that might be used, other procedures, methodologies, or techniques known to those skilled in the art may alternatively be used.

EXAMPLE 1 Regulation of NK Cells

Natural killer (NK) cells respond to IL-2 and IL-15 signaling by differentiating into fully functional effector cells that secrete antiviral cytokines required for host defense; however, the mechanisms regulating IL-2 receptor signaling by the host or pathogen remain unclear. It is demonstrated herein that the human cytomegalovirus or UL144 functions as a highly selective agonist of the inhibitory receptor, B and T lymphocyte attenuator (BTLA). UL144 binds exclusively to BTLA, subjecting NK cells to inhibitory signaling. Thus, UL144 engagement with BTLA dephosphorylates JAK1 and STAT5, decreasing the strength and duration of IL-2 receptor signaling, suppressing expression of antiviral cytokines interferon-γ and lymphotoxin-αβ. In contrast to UL144, its cellular ortholog herpesvirus entry mediator (HVEM) activates NK cell expression of IL-2Rα and CD69 via CD160. Taken together, the results reveal a novel mechanism by which BTLA limits IL-2 activation inhibiting the antiviral effector functions of NK cells, while HVEM-CD160 engagement promotes NK cell activation.

This example demonstrates that human CMV or UL144 is a specific agonist of inhibitory signaling through BTLA; UL144-BTLA inhibits IL-2 signaling resulting in diminished JAK1 phosphorylation; BTLA activation reduces NK cell expression of antiviral cytokines; and HVEM-CD160 activates NK cells.

The following experimental procedures were utilized.

Human peripheral blood cell isolation and activation.

Fresh human blood from normal healthy donors was mixed 1:1 with PBS and overlaid onto Ficoll (GE Healthcare, Uppsala, SE) for density gradient centrifugation. Peripheral blood mononuclear cells (PBMC) were isolated from buffy coats and washed twice with PBS. NK cells were further purified using EasySep Human NK Cell Enrichment Kit™ (Stemcell Technologies, Vancouver, Calif.) and confirmed to be >95% pure by CD56 staining. Cells resuspended to 1-2×10⁶ cells per ml in R10 media (RPMI 1640 with 10% heat-inactivated fetal bovine serum, antibiotics, L-glutamine and 50 μM β-mercaptoethanol) were first incubated on ice 15-30 minutes with Fc fusion proteins or hIgG₁ control. For infectious co-culture experiments NHDF cells were infected with CMV at an MOI=1 for 6 hours, washed with PBS, and mixed with pretreated PBMC at a ratio of 100:1 (PBMC:NHDF). Alternatively, pretreated cells were then activated at 37° C. in flat-bottomed plates for the indicated times and concentrations of recombinant human IL-2 (rhlL-2, Biogen, Cambridge, Mass.) or recombinant human IFN-β (R & D systems, Minneapolis, Minn.).

Antibodies and Fc Fusion Proteins.

Antibodies used to identify PBMC populations include CD19 FITC, CD8 APC, CD4 eFluor 450, BTLA PE (eBioscience, San Diego, Calif.), CD3 PE-Alexa 610 (Invitrogen, Carlsbad, Calif.), CD69 PerCP-Cy5.5, CD160 Alexa 647 (Biolegend, San Diego, Calif.), CD25 PE, and CD56 Alexa-700 (BD Biosciences, San Diego, Calif.).

Purified fusion proteins of the extracellular domains of human BTLA, HVEM, human CMV UL144 and variants and rhesus CMV UL144 with human IgG₁ Fc were produced as previously described.

Phosphatidylinositol specific phospholipase C (PI-PLC) (Invitrogen, Carlsbad, CA) was used to distinguish between the glycophosphoinositide (GPI)-linked and transmembrane forms of CD160.

Cells and surface protein expression.

EL4 and 293T cells were maintained in D10 media (DMEM with 10% heat-inactivated fetal bovine serum, antibiotics, L-glutamine and 50 μM β-mercaptoethanol). NK92 cells were maintained in NK92 media (RPMI 1640 with 12.5% heat-inactivatated fetal bovine serum, 12.5% equine serum, antibiotics, L-glutamine and 50 μM β-mercaptoethanol) supplemented with 100 U/ml rhlL-2.

EL4 cells were transduced with human BTLA ires GFP (Watanabe et al., Nat Immunol 4:670-679 (2003)) or human CD160 (Open Biosystems, Huntsville, Ala.) cloned into ires GFP retroviral plasmid by PCR amplification. Pseudotyped single infection retrovirus was produced by cotransfection of retroviral plasmid, pCG VSVg envelope protein, and Hit60 gag-pol as previously described (Sedy et al., Nat Immunol 6:90-98 (2005)). EL4 cells were sorted for GFP expression to increase the frequency of BTLA and CD160 expressing cells. 293T cells were transduced with UL144 derived from human CMV strains cloned in pND vector (Cheung et al. J Biol Chem 280:39553-39561 (2005)) by calcium phosphate transfection. UL144 mutants were produced by site-directed mutagenesis. 293T cells were transduced with human BTLA or CD160 as described above, or with de novo synthesized rhesus BTLA or CD160 (Mr. Gene, Regensburg, Del.) cloned into ires GFP retroviral plasmid by PCR amplification. BTLA mutants were produced by round-the-world PCR. 293T cells were used for experiments coexpressing BTLA and UL144 using the vectors described above, and BTLA and human HVEM in pCDNA3 (Cheung et al. J Biol Chem 280:39553-39561 (2005)). All oligonucleotides used for PCR amplification and site-directed mutagenesis are listed in Table 1.

TABLE 1 Primers used for cloning and site directed mutagenesis. Gene Primer Sequence Human CD160 Cloning hCD1605BglII AGTCAGATCTGCGTGCAGGA TGCTGTTG (SEQ ID NO: 1) Cloning hCD1603XhoI AGTCCTCGAGGGCTTACAAAG CTTGAAGGG (SEQ ID NO: 2) Rhesus BTLA Cloning RhBTLA BglII AGTCAGATCTGTGCAGGAAAT GAAGACATTG (SEQ ID NO: 3) Cloning RhBTLA XhoI AGTCCTCGAGTCAGAAACAGA CTTAACTCCTCACAC (SEQ ID NO: 4) Rhesus CD160 Cloning RhCD160 BglII AGCTAGATCTGCGTGCAGGAT GCTGATG (SEQ ID NO: 5) Cloning RhCD160 XhoI AGTCCTCGAGAAGGCTTACA AAGCTTGAAGGACC (SEQ ID NO: 6) Human CMV UL144 E27A Mutant Fiala UL144 E46 AAACCCGAAGCAGTGCAATT For AGGAAATCAGTG (SEQ ID NO: 7) E27A Mutant Fiala UL144 E46 TAATTGCACTGCTTCGGGTTT Rev GCATATTTCAG (SEQ ID NO: 8) Q33A Mutant Fiala UL144 Q52 TTAGGAAATGCGTGTTGTCCC For CCATGTAAACAAG (SEQ ID NO: 9) Q33A Mutant Fiala UL144 Q52 GGGACAACACGCATTTCCTAA For TTGCACTTCTTC (SEQ ID NO: 10) P36A Mutant Fiala UL144 P55 CAGTGTTGTGCCCCATGTAAA For CAAGGATATCGTG (SEQ ID NO: 11) P36A Mutant Fiala UL144 P55 TTTACATGGGGCACAACACTG For ATTTCCTAATTG (SEQ ID NO: 12) G41A Mutant Fiala UL144 G60 TGTAAACAAGCATATCGTGTT For ACAGGACAATGTAC (SEQ ID NO: 13) G41A Mutant Fiala UL144 G60 AACACGATATGCTTGTTTACA For TGGGGGACAACACTG (SEQ ID NO: 14) Y42A Mutant UL144F-Y42A-F CCCCCATGTAAACAAGGAGCT CGTGTTACAGGACAATG (SEQ ID NO: 15) Y42A Mutant UL144F-Y42A-R CATTGTCCTGTAACACGAGCTC CTTGTTTACATGGGGG (SEQ ID NO: 16) R43A Mutant Fiala UL144 R62A CAAGGATATGCTGTTACAGGAC For AATGTACGCAATATAC (SEQ ID NO: 17) R43A Mutant Fiala UL144 R62A TCCTGTAACAGCATATCCTTGTT For TACATGGGGG (SEQ ID NO: 18) T45A Mutant Fiala UL144 T64 TATCGTGTTGCAGGACAATGTAC For GCAATATACG (SEQ ID NO: 19) T45A Mutant Fiala UL144 T64 ACATTGTCCTGCAACACGATATC For CTTGTTTACATGG (SEQ ID NO: 20) G46A Mutant Fiala UL144 G65 CGTGTTACAGCACAATGTACGCA For ATATACGAGTAC (SEQ ID NO: 21) G46A Mutant Fiala UL144 G65 CGTACATTGTGCTGTAACACGAT Rev ATCCTTGTTTAC (SEQ ID NO: 22) G46K Mutant FUL144-G46K 5′ AAACAAGGATATCGTGTTACAAA ACAATGTACGCAATATACGAGT (SEQ ID NO: 23) G46K Mutant FUL144-G46K 3′ ACTCGTATATTGCGTACATTGTTTT GTAACACGATATCCTTGTTT (SEQ ID NO: 24) Q50A Mutant Fiala UL144 Q69 CAATGTACGGCATATACGAGTACA For ACATGTACAG (SEQ ID NO: 25) Q50A Mutant Fiala UL144 Q69 ACTCGTATATGCCGTACATTGTCCT Rev GTAACACGATATC (SEQ ID NO: 26) T52A Mutant Fiala UL144 T71 ACGCAATATGCGAGTACAACATGT For ACACTTTGCCC (SEQ ID NO: 27) T52A Mutant Fiala UL144 T71 TGTTGTACTCGCATATTGCGTACAT Rev TGTTCTGTAAC (SEQ ID NO: 28) L68A Mutant Fiala UL144 L86 GTATCAGGGGCTTACAATTGTACC For AATTGCACTG (SEQ ID NO: 29) L68A Mutant Fiala UL144 L86 ACAATTGTAAGCCCCTGATACATAC Rev GTACCGTTAG (SEQ ID NO: 30) P106A Mutant Fiala UL144 P124 TTTTCCGTTGCAGGCGTCCAACATC For ACAAGCAACG (SEQ ID NO: 31) P106A Mutant Fiala UL144 P124 TTGGACGCCTGCAACGGAAAATGA Rev CGTATAATTC (SEQ ID NO: 32) Human BTLA Q37A Mutant HuBTLAQ37Atop CATGTGATGTAGCGCTTTATATA AAGAGACAATCTGAACACTC (SEQ ID NO: 33) Q37A Mutant HuBTLAQ37Abot CTTTATATAAAGCGCTACATCACA TGATTCTTTCCCATG (SEQ ID NO: 34) L38H Mutant HuBTLAL38Htop ATGTGATGTACAGCATTATATAAAGA GACAATCTGAACACTCC (SEQ ID NO: 35) L38H Mutant HuBTLAL38Hbot TTGTCTCTTTATATAATGCTGTACATC ACATGATTCTTTCC (SEQ ID NO: 36) R42D Mutant HuBTLAR42Dtop CTTTATATAAAGGACCAATCTGAACAC TCCATCTTAGC (SEQ ID NO: 37) R42D Mutant HuBTLAR42Dbot GTGTTCAGATTGGTCCTTTATATAAAG CTGTACATCACATGATTC (SEQ ID NO: 38) E45A Mutant HuBTLAE45Atop AGAGACAATCTGCACACTCCATCTTAG CAGGAGATCC (SEQ ID NO: 39) E45A Mutant HuBTLAE45Abot AAGATGGAGTGTGGAGATTGTCTCTTT ATATAAAGCTGTAC (SEQ ID NO: 40) E57A Mutant HuBTLAE57Atop CTTTGAACTAGCATGCCCTGTGAAATA CTGTGCTAAC (SEQ ID NO: 41) E57A Mutant HuBTLAE57Abot TCACAGGGCATGCTAGTTCAAAGGGAT CTCCTGCTAAG (SEQ ID NO: 42) P59A Mutant HuBTLAP59Atop GAACTAGAATGCGCTGTGAAATACTGT GCTAACAGGC (SEQ ID NO: 43) P59A Mutant HuBTLAP59Abot GTATTTCACAGCGCATTCTAGTTCAA AGGGATCTC (SEQ ID NO: 44) K90A Mutant HuBTLAK90Atop ACAAGTTGGGCGGAAGAGAAGAACA TTTCATTTTTCATTC (SEQ ID NO: 45) K90A Mutant HuBTLAK90Abot CTTCTCTTCCGCCCAACTTGTTTGTCT ATCTTCAAGTTTTAC (SEQ ID NO: 46) V117A Mutant HuBTLAV117Atop TGTTCTGCAAATTTTCAGTCTAATCTC ATTGAAAGC (SEQ ID NO: 47) V117A Mutant HuBTLAV117Abot GATTAGACTGAAAATTTGCAGAACAG CGGTATGACCC (SEQ ID NO: 48) N118F Mutant HuBLTAN118Ftop GCTGTTCTGCATTTTTTCAGTCTAATCT CATTGAAAGC (SEQ ID NO: 49) N118F Mutant HuBTLAN118Fbot TAGACTGAAAAAATGCAGAACAGCGG TATGAC (SEQ ID NO: 50) F119A Mutant HuBTLAF119Atop GTTCTGCAAATGCTCAGTCTAATCTCA TTGAAAGCCAC (SEQ ID NO: 51) F119A Mutant HuBTLAF119Abot GAGATTAGACTGAGCATTTGCAGAAC AGCGGTATG (SEQ ID NO: 52) S121H Mutant HuBTLAS121Htop CAAATTTTCAGCATAATCTCATTGAAA GCCACTCAAC (SEQ ID NO: 53) S121H Mutant HuBTLAS121Hbot CAATGAGATTATGCTGAAAATTTGCAG AACAGCG (SEQ ID NO: 54) H127D Mutant HuBTLAH127Dtop CATTGAAAGCGACTCAACAACTCTTTA TGTGACAGATG (SEQ ID NO: 55) H127D Mutant HuBTLAH127Dbot GTTGTTGAGTCGCTTTCAATGAGATTA GACTGAAAATTTG (SEQ ID NO: 56) S128H Mutant HuBTLAS128Htop TGAAAGCCACCATACAACTCTTTATGT GACAGATGTAAAAAG (SEQ ID NO: 57) S128H Mutant HuBTLAS128Hbot AAGAGTTGTATGGTGGCTTTCAATGAG ATTAGACTG (SEQ ID NO: 58)

Binding Assays

Flow cytometric binding assays were performed as previously described (Cheung et al. J Biol Chem 280:39553-39561 (2005)). Cells were incubated with Fc ligands for 30 minutes at 4° C. in buffer (PBS with 2% FBS), washed twice and incubated with donkey anti-human Fc APC (Jackson Immunoresearch, West Grove, Pa.) for 15 minutes at 4° C. in buffer, washed twice and analyzed. Specific mean fluorescence intensity (MFI) was calculated by subtracting experimental cellular MFI from control cellular MFI.

BTLA Mutagenesis and Epitope Mapping

Anti-human BTLA used for epitope mapping include J168 (BD Biosciences, San Diego, Calif.), MIH26 (eBioscience, San Diego, Calif.), and monoclonal (6F4) and polyclonal rat anti-human BTLA produced as previously described (Cheung et al., J Immunol 183:7286-7296 (2009)). These were detected by goat anti-mouse APC (BD Bioscience, San Diego, Calif.) and donkey anti-rat APC (Jackson Immunoresearch, West Grove, Pa.).

Surface Plasmon Resonance Kinetic Affinity Measurement

Human BTLA Fc ligand was immobilized onto a CM5 sensor chip to 150 relative units using amine coupling. Sensograms were collected at 25° C. at a flow rate of 30 μl/min, and specific binding was determined by subtraction of control from ligand channels. Indicated concentrations of analyte were injected from vials cooled to 7° C. Data collection included 90 μl of analyte for 3 minutes followed by disassociation for 15 minutes. The sensor surface was regenerated after each cycle with a 30 second pulse of 15 μl 10 mM Glycine pH 2.5. Affinity measurements were made by analyzing both the first 10 seconds following analyte injection and disassociation using the kinetic analysis module of the BIAevaluation™ software (version 4.1) with both the Langmuir and the Bivalent fit models.

Western Analysis

NK92 cells used for IL-2 activation were first resuspended in NK92 media without IL-2 overnight followed by resuspension in serum-free media for at least 4 hours. These cells were then washed and resuspended in PBS and preincubated with Fc fusion proteins similar to human cell experiments outlined above. Preincubated cells were aliquoted to 0.5-1×10⁶ cells per condition were activated at 37° C. with the indicated concentrations of rhlL-2 and for the indicated times. Activation reactions were quenched with ice cold PBS and lysed in RIPA buffer at 4° C. for 20 minutes and centrifuged at 14,000 rpm, 4° C. Extracts were boiled in SDS loading buffer containing 1% β-mercaptoethanol for 5 minutes and resolved by SDS-PAGE on 10% Bis-Tris gels (Invitrogen, Carlsbad, Calif.). Proteins were transferred using tank method to PVDF membrane and blocked with 1% ovalbumin in TBS-T buffer, and blotted with either phospho-JAK1, phospho-AKT (S473), phospho-extracellular-signal regulated kinase (ERK) 1/2, total AKT (Cell Signaling, Danvers, Mass.), phospho-signal-transducer and activator of transcription (STAT) 5a/b (Millipore, Temecula, Calif.), total JAK1, total ERK2 (Santa Cruz, Santa Cruz, Calif.), or total actin followed by anti-rabbit HRP (GE Healthcare), anti-mouse HRP, or anti-mouse AP (Santa Cruz, Santa Cruz, Calif.), and visualized by enhanced chemiluminescence (Thermo Scientific, Rockford, Ill.) or by BCIP®/NBT substrate deposition (Sigma-Aldrich, Saint Louis, Mo.).

Quantitative RT-PCR Analysis

Human NK cells stimulated with IL-2 and UL144-Fc were first washed with PBS and then RNA was harvested using RNeasy® Mini kit (Qiagen, Valencia, Calif.). cDNA was transcribed from RNA using the iScript™ cDNA Synthesis kit (Bio-Rad, Hercules, Calif.). Transcripts were amplified in 10 μl volume using 300 nM of primers in Power SYBR® Green PCR Master Mix on an ABI 7900HT Real-Time PCR System and specific products were analyzed using SDS v2.3 (Life Technologies, Carlsbad, Calif.). Primers used for quantitative RT-PCR analysis are shown in Table 2.

TABLE 2 Primers used for quantitative RT-PCR. Gene Primer Sequence LTA Forward Lta F ACTACCGCCCAGCAGTGT (SEQ ID NO: 59) Reverse Lta R GTGTCATGGGGAGAACCAA (SEQ ID NO: 60) LTB Forward Ltb F GGCGGTGCCTATCACTGT (SEQ ID NO: 61) Reverse Ltb R TTCTGAAACCCCAGTCCTTG (SEQ ID NO: 62) LIGHT Forward L Fwd QPCR SS TCTCTTGCTGTTGCTGATGG (SEQ ID NO: 63) Reverse L Rev QPCR SS CTCGTGAGACCTTCGCTCTT (SEQ ID NO: 64) TNF Forward Tnfa F CAGCCTCTTCTCCTTCCTGAT (SEQ ID NO: 65) Reverse Tnfa R GCCAGAGGGCTGATTAGAGA (SEQ ID NO: 66) TNFRSF14 Forward HuHVEM RTP (+) AGCAGCTCCCCACTGGGTATG (SEQ ID NO: 67) Reverse HuHVEM RTP (-) GATTAGGCCAACTGTGGAGCA (SEQ ID NO: 68) BTLA Forward hBTLA Frwd GCCTCTACTCATCACTACCTGTTTTC (SEQ ID NO: 69) Reverse hBTLA Rev TCAGAGAGTTCATTTTGCTTTCC (SEQ ID NO: 70) CD160 Forward HuCD160For CCTCACTACATCCGTGAACTCC (SEQ ID NO: 71) Reverse HuCD160Rev CTGCTGGTATCCTTGGCTTC (SEQ ID NO: 72) SOCS1 Forward SOCS1 Fwd CCCCTGGTTGTTGTAGCAG (SEQ ID NO: 73) Reverse SOCS1 Rev GTAGGAGGTGCGAGTTCAGG (SEQ ID NO: 74) SOCS3 Forward SOCS3 Fwd CTTCGACTGCGTGCTCAAG (SEQ ID NO: 75) Reverse SOCS3 Rev GTAGGTGGCGAGGGGAAG (SEQ ID NO: 76) L32 Forward L32 F GGATCTGGCCCTTGAACCTT (SEQ ID NO: 77) Reverse L32 R GAAACTGGCGGAAACCCA (SEQ ID NO: 78)

The following experimental results were observed.

HVEM and UL144 bind BTLA with similar affinity.

Two-fold dilutions of human HVEM Fc human CMV UL144 Fc were injected over human BTLA Fc immobilized to dextran sulfate and a control channel in replicate at the indicated concentrations. Representative traces of the first minute following injection and 4 minutes of dissociation of the analyte are shown. K_(D) was calculated from modeling both a 1:1 and 1:2 fit. Rate constants calculated using a 1:2 model of ligand to analyte binding showed very low secondary k_(on)/k_(off) rate constants for both human and rhesus CMV UL144, indicating that UL144 may preferentially bind BTLA as a monomer

HVEM and UL144 bind the same surface of BTLA.

EL4 cells transduced with wild-type or mutant human BTLA were stained with 10 μg/ml of HVEM Fc or human CMV UL144 Fc or with polyclonal or monoclonal antibodies specific for human BTLA as indicated. Fusion proteins were detected with anti-human Fc and anti-BTLA was detected with anti-rat (6F4) or anti-mouse (J168, MIH26). From top to bottom graphs are specific MFI staining of HVEM Fc, UL144 Fc, J168 anti-BTLA, 6F4 anti-BTLA, and either polyclonal anti-BTLA (FIG. 2A) or MIH26 anti-BTLA (FIG. 2B) staining on cells within the GFP⁺ gate showing that both HVEM Fc and human CMV UL144 Fc use residues Q37, R42, P59 and H127 but not E45, E57, N118, F119 and S121, that residue R42 is required to bind anti-human BTLA J168, and that residue E57 is required to bind anti-human BTLA MIH26. The K90A mutation results in poor protein expression. In FIG. 2C the structure of BTLA is shown complexed to HVEM (top) and rotated 90° about the y-axis complexed with a second BTLA Ig molecule (bottom). (Protein Data Bank ID code 2AW2, Structures visualized using The PyMOL Molecular Graphics System, Version 0.99rc6, Schrödinger, LLC.) The surface of BTLA is shown in gray together with either HVEM (magenta) or a second BTLA Ig domain (light blue) as a main chain backbone with BTLA surface mutations indicated as shown. BTLA residues Q37, R42, P59 and H127 that are required for optimal binding of HVEM and UL144 are colored dark red. Residues E45 and E57 localized within the putative BTLA dimerization surface are colored orange. Residues N118, F119, and S121 located within the F-G loop of the BTLA Ig domain are colored teal. Residue K90 that is required for optimal surface expression is colored yellow.

BTLA complexes in cis prevent binding to HVEM and UL144 Fc.

293T cells transfected with BTLA alone or together with HVEM or human CMV UL144 were stained with the indicated concentrations of HVEM Fc (FIG. 3A) or human CMV UL144 Fc (FIG. 3B). Binding curves show a specific block of HVEM Fc or human CMV UL144 Fc binding to BTLA when either HVEM or human CMV UL144 is coexpressed. 293T cells transfected with HVEM (FIG. 3C) or human CMV UL144 (FIG. 3D) alone or together with wild-type, R42D, or E57A BTLA were stained with the indicated concentrations of BTLA Fc. Binding curves show a specific block of BTLA Fc binding to HVEM or human CMV UL144 when wild-type BTLA is coexpressed, that is reversed only when the R42D mutant is coexpressed with HVEM and not with human CMV UL144.

HVEM but not human CMV UL144 binds to human CD160.

To address whether UL144 binds CD160, saturating binding of HVEM-Fc to cells expressing human BTLA or CD160 was measured and similar disassociation constants were found (FIG. 4A). UL144-Fc also bound cells expressing BTLA, but failed to bind to CD160 (FIG. 4B). EL4 cells expressing human BTLA or human CD160 were stained with the indicated concentrations of HVEM-Fc (FIG. 4A) or human CMV UL144 Fc (FIG. 4B). Binding curves show specific binding of HVEM-Fc to BTLA and CD160, while human CMV UL144 binds only to BTLA. EC50 values were calculated using the nonlinear regression four parameter (variable slope) analysis module of GraphPad Prism™ software (version 5.0b).

HVEM-Fc Co-Stimulates NK Responses to CMV

To test how HVEM and its viral ortholog UL144 function to regulate immune responses during viral infection, expression of activation markers in cells from human peripheral blood mixed with CMV infected fibroblasts was monitored (FIG. 7). All subsets of PBMC induced CMV-dependent expression of CD69 that steadily increased throughout the duration of the co-cultures. However, unique enhancement of CD69 expression in CD56^(dim) NK cells at days 1 and 3 in PBMC treated with HVEM-Fc (FIG. 5A) was observed. A similar enhancement of CD107a expression in CD56^(dim) NK cells after one day of culture (FIG. 5B) was observed. Thus, HVEM-Fc specifically enhances early activation of CD56^(dim) NK cells during responses to CMV.

CMV induced NK cell activation correlates with CD160 expression.

To identify which HVEM or UL144 ligands were present in lymphocytes, human peripheral blood was examined for BTLA, CD160, HVEM and LIGHT expression. BTLA and CD160 expression was inversely correlated on most PBMC subsets, while HVEM was broadly expressed by all PBMC, and LIGHT showed specific expression in monocytes, CD8⁺ T cells and weak expression in NK cells (FIG. 6A-D). In particular, B cells showed the highest BTLA expression and among the lowest CD160 expression. In contrast CD56^(dim) NK cells showed the highest CD160 expression and among the lowest BTLA expression. T cells and monocytes expressed intermediate levels of BTLA and CD160, while CD56^(bright) NK cells expressed low levels of both BTLA and CD160. The expression of HVEM ligands was compared to the increased CD69 percent co-stimulated by HVEM-Fc (FIG. 6E-G). Co-stimulation by HVEM-Fc was most associated with CD56^(dim) NK cell CD160, while BTLA and LIGHT were expressed at very low levels. Additionally, co-stimulation by HVEM-Fc was not associated with the percent of NK cells expressing NKG2C, or CMV seropositivity of the donors (FIG. 6H-I), indicating that HVEM co-stimulation was independent of the donor CMV infectious status but did correlate with CD160 levels in CD56^(dim) NK cells.

Human CMV UL144 binds BTLA but not CD160.

Whether the CMV protein UL144 could bind CD160 by measuring the binding of HVEM- or UL144-Fc proteins to cells expressing human BTLA or CD160 (FIGS. 5A-B) was tested next. UL144-Fc only bound cells expressing BTLA but not CD160, while HVEM-Fc bound BTLA and CD160 with similar disassociation constants and required overlapping surfaces to bind these receptors as shown with the Y61A mutation (FIG. 5C). Whether the loss of interaction between UL144 and CD160 was due to a reduced affinity using a UL144 mutant (G46K) identified while mapping the binding surface of UL144 that bound BTLA with higher affinity (FIG. 5) was also sought to be determined. However, CD160 again failed to show any binding (FIG. 5D), although BTLA showed robust binding to the UL144 G46K mutant. The ectodomain of UL144 is highly polymorphic across different strains of human CMV with five distinct isoforms diverging up to 36% in their amino acid sequence (Table 3). UL144 selectivity for BTLA was examined throughout these diverse sequences using representative UL144 variants derived from clinical human CMV strains (FIG. 5E). Despite the extensive sequence divergence, BTLA-Fc bound all UL144 variants, whereas CD160-Fc uniformly failed to bind any of the UL144 variants. However one exception was noted, UL144 from Rhesus CMV bound human and rhesus CD160 with low affinity (FIGS. 5D-F). This interaction likely represents a divergence between human and rhesus CMV since primate BTLA and CD160 are highly similar (Tables 4-5). In contrast, HVEM and UL144 showed remarkably similar affinity for BTLA, overlapping BTLA binding surfaces, and competitive binding for BTLA coexpressed in cis with HVEM (FIG. 2, FIG. 15, Tables 6-7). Together these data show the highly selective nature of UL144 that mimics HVEM binding to BTLA but not to CD160. Thus, while both BTLA and CD160 bind HVEM with similar affinity (FIG. 7A), in resting NK cells CD160 is the predominant HVEM receptor.

TABLE 3 Alignment of CRD1 and 2 from primate HVEM and CMV UL144 sequences. UL144 HCMV HVEM Gr 1A Gr 1B Gr 1C Gr 2 Gr 3 ChCMV RhCMV Rhesus Human UL144 HCMV Gr 1A *** 95.9 98.6 72.6 76.7 45.2 41.7 38.4 42.5 Gr 1B 4.2 *** 94.5 72.6 75.3 45.2 43.1 39.7 43.8 Gr 1C 1.4 5.7 *** 71.2 75.3 45.2 40.3 39.7 43.8 Gr 2 34.1 34.1 36.3 *** 72.6 46.6 41.7 41.1 41.1 Gr 3 27.9 29.9 29.9 34.1 *** 49.3 41.7 38.4 43.8 ChCMV 93.6 93.6 93.6 89.5 81.7 *** 43.8 40.5 48.6 RhCMV 105.4 100.6 110.4 105.4 105.4 98 *** 52.7 55.4 HVEM Rhesus 117.9 112.5 112.5 107.4 117.9 109.5 72.9 *** 84.6 Human 102.6 98 98 107.4 98 83.5 66.5 17.3 *** Percent similarity in upper triangle, percent divergence in lower triangle.

TABLE 4 Percent similarity between primate BTLA extracellular domain. Human Chimpanzee Rhesus BTLA BTLA BTLA Human BTLA *** 100 89 Chimpanzee *** *** 89 BTLA Rhesus BTLA *** *** ***

TABLE 5 Percent similarity between primate CD160 extracellular domain. Human Chimpanzee Rhesus CD160 C160 CD160 Human CD160 *** 100 90 Chimpanzee *** *** 90 CD160 Rhesus CD160 *** *** ***

TABLE 6 Monovalent and bivalent kinetic rate constants for Fc fusion protein binding. Analyte HuCMV RhCMV HVEM Fc UL144 Fc UL144 Fc Monovalent Analysis k_(a) (×10⁴ M⁻¹s⁻¹) 3.74 1.61 2.28 k_(d) (×10⁻³ s⁻¹) 6.60 4.76 29.5 K_(D) (nM) 177 295 1300 Bivalent Analysis k_(a1) (×10⁴ M⁻¹s⁻¹) 1.53 0.781 1.66 k_(d1) (×10⁻³ s⁻¹) 9.02 5.10 31.0 k_(a2) (×10⁻³ M⁻¹s⁻¹) 57.3 0.0139 0.0192 k_(d2) (s⁻¹) 2.05 0.00289 0.129

TABLE 7 Summary of human BTLA Mutations. Anti- Anti- Anti- BTLA BTLA HuCMV BTLA BTLA 6F4 J168 MIH26 HVEM Fc UL144 Fc Wild-Type + + + + + Q37A + + + − +/− R42D + − + − − E45A + + + + + E57A + + − + + P59A + + + − − K90A +/− +/− +/− − − N118F + + + + + F119A + + + + + S121H + + + + + H127D + + + − − A117V + + + +/− +/− A117V, Q37A + + + − − A117V, L38H + + + − − A117V, R42D + − + − − A117V, P59A + + + − − A117V, + + + − − H127D A117V, S128H + + + − −

TABLE 8 Summary of human HVEM Mutations. Anti- LIGHT- HVEM HVEM FLAG BTLA-Fc CD160-Fc Wild-Type + + + + P59S n.d. + + − G60D + − − − Y61C + + − − G72P n.d. + − − T82P n.d. − − − R109W + + + − G232S n.d. + + + n.d.—not done.

HVEM-Fc co-stimulates cytokine activation of NK cells.

Detection of virus by dendritic cells and macrophages results in early production of cytokines that prime the effector function of NK cells and help to control infection. To test how HVEM and its viral ortholog UL144 regulate cytokine activation of NK cells IL-2-induced expression of activation markers in lymphoid cells from human peripheral blood was monitored. Notably, HVEM-Fc consistently enhanced the number of CD56^(dim) NK cells expressing CD69 and IFN-γ at low and high doses of IL-2 (FIG. 8). In contrast, UL144-Fc inhibited NK cell expression of CD69 but only at low doses of IL-2. CD69 induction in CD56^(bright) NK cells in response to HVEM-Fc or UL144-Fc was statistically significant although the magnitude of CD69 or IFN-γ induction in CD56^(bright) or cytotoxic CD8⁺ T cells did not appreciably change. Similar co-stimulation of CD69, CD25 and CD107a expression in purified CD56^(dim) NK cells in response to IL-2 and IFN-β treatment was observed, indicating that accessory cells were not required for the activity of HVEM-Fc in NK cells (FIGS. 9A-D). Increased levels of IFN-γ and IL-8 protein produced by HVEM-Fc treated pure CD56⁺ cells stimulated with IL-2 and IFN-β (FIGS. 9E-F) were found. Additionally increased TNF-α and LT-α production in IL-2 stimulated NK cells treated with either HVEM-Fc or UL144-Fc was observed. Thus, HVEM-Fc co-stimulation drives inflammatory cytokine production in NK cells, while UL144-Fc inhibits CD69 induction while augmenting TNF cytokine production.

BTLA inhibits cytokine signaling in NK cells.

The impact of HVEM-Fc or UL144-Fc on NK cell function using the NK92 cell line as a model of activated NK cells was tested next. Similar to peripheral blood NK cells, the NK92 cell line displayed abundant CD160 and low BTLA levels (FIGS. 10A-B). Human NK92 cells respond to IL-2 by phosphorylation of the kinase JAK1 leading to the activation of STAT5 (FIG. 10C). In this regard, IL-2 receptor stimulation signals rapid JAK1 and STAT5 phosphorylation peaking at 30 minutes followed by a decrease in activation through 60 minutes Enhanced phosphorylation of both JAK1 and STAT5 following HVEM-Fc treatment, and decreased phosphorylation of JAK1 and STAT5 following UL144-Fc treatment of NK92 cells, indicating that HVEM and UL144 ligation targets IL-2 activation proximal to receptor activation was observed. Reduced IL-2-induced phosphorylation of JAK1 and STAT5, and of the downstream kinase AKT using an agonistic anti-BTLA antibody (MIH26) was observed, demonstrating that the inhibitory effect of UL144-Fc was through BTLA (FIG. 10D). Additionally, reduced IFN-β-induced STAT1 phosphorylation following anti-BTLA treatment (FIG. 10E) was observed. Thus, BTLA regulates early signaling events proximal to IL-2 and IFN-β receptor activation.

HVEM and UL144 regulate NK activation by target cells.

Whether HVEM- or UL144-Fc could regulate activation of the NK92 cell line by the K562 erythroleukemia cell line was tested next. Co-culture of NK92 cells with K562 cells results in rapid ERK phosphorylation at 5 minutes and AKT phosphorylation at 20 minutes (FIG. 11A). HVEM-Fc treatment of the NK92 cells co-stimulated enhanced and sustained ERK phosphorylation at 5 and 20 minutes and more rapid and robust AKT phosphorylation at 5 and 20 minutes. In contrast, UL144-Fc treatment of the NK92 cells quenched ERK and AKT phosphorylation. When NK92 cells were treated with a mutant HVEM-Fc which ablates CD160 binding prior to co-culturing with K562 cells, this mutant was found to co-stimulate reduced AKT and ERK phosphorylation as compared to the wild-type HVEM-Fc (FIG. 1B). Whether co-stimulation of NK92 cells involved Fc receptor binding using K562 cells transduced with HVEM or control vector was tested next. NK92 cells co-cultured with HVEM-expressing K562 cells also show co-stimulated ERK and AKT phosphorylation as compared to control K562 cells (FIG. 11C). Thus, HVEM costimulates cellular activation of NK cells through CD160, while UL144 inhibits NK cell activation by target cells.

Selective HVEM mutations distinguish ligand interactions.

A recent report has identified mutations in TNFRSF14 as a frequent alteration in follicular B cell lymphoma. While many of the alterations result in nonfunctional proteins, several appear to be produced as full length transcripts. These mutations were expressed and their interactions with HVEM ligands LIGHT, BTLA and CD160 were tested. 293 cells transfected with wild-type HVEM, G60D, Y61C, R109W mutant HVEM or control vector were stained with anti-HVEM, LIGHT-FLAG with anti-FLAG antibody, BTLA-Fc with anti-Fc, or CD160-Fc with anti-Fc. All mutants were equivalently expressed. Five of the seven (71%) mutants retained LIGHT binding with G60D and T82P being the exception. Three of the mutants retained BTLA binding (43%). Notably, only one of the mutants (G232S) (14%) retained CD160 binding. Thus, in human lymphoma in which full length HVEM is produced, HVEM interactions with CD160 are the most targeted mutation.

CD160 activates NK cell cytolysis and production of interferon-γ, TNF-α, and IL-6 by engaging HLA-C. While BTLA activation reduces CD3ζ phosphorylation in T cells and Syk, BLNK, and PLCγ2 phosphorylation in B cells, the function of BTLA in NK cells has not been established. Thus, human CMV may have evolved UL144 as a BTLA specific ligand to inhibit lymphoid cell activation, and specifically to diminish NK cell activation without triggering effector functions associated with HVEM activation.

Here, a mechanism is revealed which is used by human CMV to inhibit cytokine responsiveness in NK cells by exclusively activating BTLA without triggering CD160 activation. Unlike HVEM, which engages BTLA, CD160, LIGHT, LTα and gD of herpes simplex virus, the human CMV protein UL144 only binds BTLA. Importantly, UL144 and BTLA decreased signaling directly, as well as IL-2 responsiveness by decreasing expression of the IL-2Rα chain (CD25) leading to corresponding decrease in CD69 expression. NK cells express high levels of CD160, and therefore UL144 appears to have evolved to avoid binding to CD160 in order to specifically access BTLA. HVEM, in contrast to UL144, serves as an activating ligand for CD160, which acts dominantly in NK cells. CD160 engagement of MHC-1 can also activate NK cells. Mechanistically, UL144/BTLA signaling inhibits JAK1 activation by IL-2 and IFN-β, limiting NK cell expression of LT-β and interferon-γ, thus attenuating two significant anti-viral effector functions critical for host defense to CMV.

The coexpression of CD160 and BTLA in NK cells may determine whether HVEM binding delivers an activating or inhibitory signal. The similar affinity of HVEM for CD160 and BTLA suggests that abundant NK cell CD160 is preferentially bound to HVEM in the environment. This model of receptor accessibility suggests that most surface BTLA is unbound (free). UL144 bypasses CD160 directly accessing inhibitory signaling through BTLA, a key feature of inhibition of NK cell activation.

The results indicate that HVEM promotes NK cell activation, consistent with the idea that CD160 is an activating receptor. Recent work has demonstrated the presence of an alternative splice variant of CD160 containing a cytoplasmic tail and activating motifs (ITAM). It was determined that the majority (˜80%) of CD160 is GPI-linked, while the phospholipase uncleavable fraction most likely represents transmembrane CD160, however this feature remains to be established. CD160 was also shown to act as an inhibitory receptor in a fraction of CD4⁺ T cells notably lacking the transmembrane variant, however it remains unclear how GPI-linked proteins initiate inhibitory signaling. UL144-BTLA inhibition of JAK1 phosphorylation is consistent with activation and recruitment of BTLA-SHP1 to the IL-2 receptor-β chain resulting in its dephosphorylation. UL144/BTLA facilitates the capacity of SHP1 to inhibit IL2Rb2 signaling. It remains to be determined whether the specific target of BTLA is JAK1 or the IL-2 receptor itself. Interestingly SHP1 has been linked to several JAK1-activating cytokine pathways including IL-4, IL-13 and type I interferon, and it is possible that through UL144 CMV broadly affects cytokine activation in a similar manner to those of other viral proteins.

Common γ chain signaling is absolutely required for NK cell development, maturation, and possibly memory formation primarily in response to IL-15. It may be that the role of UL144 during infection is to attenuate these homeostatic signals, thus decreasing the frequency of CMV-specific NK cells and increasing the number of surviving infected cells able to produce infectious virus. Interestingly, deregulation of IL-2 signaling in the absence of BTLA was proposed as a possible mechanism for increased homeostatic expansion of BTLA-deficient CD8⁺ T cells. The results that CMV-UL144 blocks interferon-γ expression shows how CMV can circumvent IL-2 stimulated interferon IFNγ in NK cells. Moreover, the UL144 inhibition of LTαβ in NK cells may impact the production of IFNαβ in virus-infected stromal cells. Therefore in addition to broadly dampening activating signals CMV-UL144 may regulate anti-viral cytokine production to promote viral replication and spread.

The uniform BTLA selectivity among all UL144 variants implies it has a particularly forgiving structure, however, the factors that drive hypervariability of the UL144 ectodomain remain elusive. BTLA-expressing T cells can be inhibited by HVEM expressed by antigen presenting cells, regulatory T cells, or in mucosal epithelium. In contrast, CD160 activation by MHC class I molecules contributes to T cell costimulation and increased NK cell cytotoxicity and cytokine production mediated by enhanced Syk, AKT, and ERK activation. Interestingly, it was found that within follicular lymphoma the most common secondary karyotypic alteration at 1p36 is due to deletions or mutations in TNFRSF14, and that patients with these additional changes are associated with worse prognosis. In accordance with the cancer immunoediting model HVEM-expressing tumors may be eliminated by NK or CD8⁺ T cells through CD160-HVEM interactions while HVEM-deficient tumors may escape immunosurveillance and progress to acquire additional mutations resulting in poor clinical outcome. The association between different strains of CMV and disease outcome in congenital or postnatal infection is controversial. Nevertheless, there continue to be reports that specific CMV variants encoding unique UL144 sequences may be associated with termination of pregnancy, or in newborns viremia, symptomatic infection and developmental sequelae. Thus, regulation of HVEM-BTLA-CD160 may represent a common mechanism of immune evasion by pathogens, which by extension is a potential target for therapeutic manipulation to control inflammatory responses.

The previous results demonstrate that BTLA inhibitory signaling predominates using an HVEM mutein that avoids CD160. These results predict that that antagonists of HVEM binding to CD160 in cis or trans on NK cells and other effector cells such as memory T cells will also promote the inhibitory action of HVEM to suppress inflammation. Specific antagonists would include monovalent fragments of antibodies, and other protein based inhibitors. These antagonists would be selected by assays which utilize disruption of the HVEM CD160 interaction resulting in inhibition of effector cell activation as measured by cytolysis, cytokine expression or changes in other markers of inflammatory action such as CD69, CD25, LTαβ, and interferon regulated genes.

EXAMPLE 2 Treatment of Crohn's Disease Using HVEM Variants

Dysregulation of the immune system contributes to the pathogenesis of inflammatory bowel diseases (IBD) including Crohn's Disease and ulcerative colitis. In these diseases, hyper-activated T cells and innate lymphoid cells mediate tissue destructive processes in mucosal tissues. The TNF superfamily of cytokines and their cognate receptors have emerged as clinically relevant targets in IBD. The TNF receptor, herpesvirus entry mediator (HVEM; TNFRSF14) is unique in this superfamily because it activates both inflammatory and inhibitory signaling, mediating immune system homeostasis. It has been demonstrated that specifically targeting the inhibitory ligand of HVEM, B and T lymphocyte attenuator (BTLA) with protein-based therapeutics suppresses intestinal inflammation. Specific HVEM polypeptide variants targeting BTLA that attenuates persistent immune and inflammatory processes and reestablishes immunologic homeostasis are envisioned. The proof of mechanism study will target patients with Crohn's disease and ulcerative colitis. IBD patients refractory to steroid and TNF inhibitors therapy is a significant unmet medical need. The treatment goal is to induce clinical remission in these IBD patients by targeting the HVEM-BTLA pathway to restore immune homeostasis.

Crohn's disease and ulcerative colitis are two idiopathic relapsing inflammatory bowel disorders. Ulcerative colitis is a non-transmural inflammatory disease that is restricted to the colon, whereas Crohn's disease is a transmural inflammatory disease of the mucosa that may affect discontinuous regions along the entire gastrointestinal tract from the mouth to the anus with complications including strictures, abscesses, or fistulas. The chronic inflammatory disorder is frequently associated with disease complications and extraintestinal conditions. The annual incidence of hospitalizations in Crohn's disease is 20%. Half of the patients require surgery within 10 years after diagnosis and the risk of postoperative recurrence is 44-55% after 10 years.

Current treatment regimes involve progressive dosing with 5-aminosalicylic acid compounds, corticosteroids, TNF inhibitors, and eventually surgical intervention. Induction of remission is the main therapeutic goal followed with a shift to maintenance dosing. Although TNF antagonists are used in treating Crohn's disease and ulcerative colitis, the lack and/or loss of therapeutic responses in a substantial portion of patients remains a clinical challenge. Recently there have been advances in the understanding of the pathophysiology of IBD including both dysregulated activation of the acquired immune system, as well as innate immune system and intestinal epithelium involvement. These advances have opened new opportunities to control IBD. The therapeutic paradigm is shifting beyond simple immunosuppression to the reinforcement of the intestinal barrier. New agents that target inflammatory pathways are therefore needed.

New evidence indicates that specifically targeting the HVEM-BTLA pathway will impact both T cell and innate inflammatory cells in a physiological fashion that reflects the natural protective mechanisms of mucosal epithelia cells.

The HVEM polypeptide variants will specifically target the HVEM-BTLA pathway to attenuate inflammatory pathways and pathologic immune responses.

HVEM (TNFRSF14) is a key component of the cytokine network that includes TNF, Lymphotoxin (LT)-α, LTβ, and LIGHT (TNFSF14) and their cognate receptors TNFR1, TNFR2, and LTβR. This network regulates innate and adaptive inflammatory responses. HVEM is unique in the TNF Receptor family because it binds ligands in the TNF family and the Ig superfamily HVEM binds LIGHT and LTα, and two co-receptors in the Ig superfamily, B and T lymphocyte attenuator (BTLA) and CD160. Recent evidence indicates that signals generated by HVEM depend on the context of its ligands expressed in trans or in cis.

HVEM-BTLA Expression. BTLA expression is restricted to the hematopoietic compartment. HVEM is coexpressed with BTLA in hematopoietic cells but is also detected in mucosal epithelia and endothelial cells. In contrast, CD160 is also coexpressed with HVEM and BTLA but is prominently expressed in NK cells, NKT cells, and subsets of memory CD8 T cells, intestinal intraepithelial T cells and mast cells, whereas naïve T cells and B cells do not express CD160. BTLA is uniquely engaged by HVEM as indicated by the lack of staining of BTLA-Fc in HVEM−/− mice. Thus, the proposed modified HVEM-Fc will only engage a single ligand, BTLA, which should exclusively drive inhibitory signaling.

The HVEM-BTLA Inhibitory Pathway. HVEM functions as a switch between proinflammatory (LIGHT-HVEM) and inhibitory signaling (HVEM-BTLA). A growing number of studies revealed targeting BTLA alters T and B cell immune responses, and the results herein demonstrate BTLA inhibits innate lymphocyte responses, e.g., NK cells by altering IL-2-related cytokine signaling, thus suppressing nonspecific inflammation.

HVEM-Fc Polypeptide Variant.

A specific BTLA-targeted polypeptide is to be developed, an engineered form of the human HVEM extracellular domain fused to a human IgG hinge and Fc domain. The receptor domain of the HVEM-Fc fusion will be engineered to remove LIGHT, LTα and CD160 binding activities, retaining specificity for BTLA and thus uniquely retain its anti-inflammatory signaling action. This molecule hereafter referred to as HVEM-Fc mutein HVEM-Fc polypeptide variant.

HVEM-Fc Mutein. The variant will contain a truncated form of the ˜164 amino acid HVEM extracellular domain containing the first two cysteine-rich domains (CRDs). HVEM-Fc mutein will have binding activity for human BTLA through its CRD1 region, and will contain one or more mutations in CRD1 ablating binding to CD160. The Fc portion of the biologic will be a C-terminal human IgG1 effectorless Fc domain Key residues in HVEM that separate BTLA and CD160 binding have been identified.

Engineering of HVEM-Fc Mutein.

The HVEM variant, although based on HVEM, will be deficient in LIGHT, LTα and CD160 binding. Removal of CRD4 and most or all of CRD3 will ablate binding of the first two ligands. BTLA binding is known to be mediated by CRD1. For these reasons, two Fc fusion constructs are proposed as starting points for the engineering of the BTLA-specific HVEM agonist, the first containing the first two CRDs (HVEM(39-120 with reference to SEQ ID NO: 79)), and the second containing CRD1, 2 and half of CRD3 (HVEM(39-141 with reference to SEQ ID NO: 79). Both will be expressed and purified for assessment of their binding properties for BTLA, CD160, LIGHT and LTα as well as their physicochemical characteristics. Neither construct is expected to bind to LIGHT or LTα. One of the two molecules will then be selected for engineering to remove CD160 binding while maintaining BTLA binding. As a starting point, positions P59 and R109, which bind BTLA-Fc and not CD160-Fc in a FACS-based assay, will be assessed as sites for mutagenesis.

Although the invention has been described with reference to the above example, it will be understood that modifications and variations are encompassed within the spirit and scope of the invention. Accordingly, the invention is limited only by the following claims. 

1. An isolated herpesvirus entry mediator (HVEM) polypeptide variant, wherein the variant specifically binds BTLA and does not bind CD160, wherein the variant comprises a wild-type HVEM protein having at least one amino acid substitution at residue position 59, 60, 61, 72, 82, 109 or
 232. 2. (canceled)
 3. The HVEM polypeptide variant of claim 1, wherein the variant comprises one or more of P59S, G60D, Y61C, G72P, T82P, R109W and G232S.
 4. The HVEM polypeptide variant of claim 1, wherein the variant is a truncated wild-type HVEM protein having at least one amino acid substitution.
 5. The HVEM polypeptide variant of claim 4, wherein the variant comprises the extracellular domain of the wild-type HVEM protein.
 6. The HVEM polypeptide variant of claim 5, wherein the variant comprises at least one cysteine rich domain (CDR) of the extracellular domain of the wild-type HVEM protein. 7.-10. (canceled)
 11. The HVEM polypeptide variant of claim 1, wherein the variant comprises an amino acid substation at residue position 59 or position
 109. 12.-19. (canceled)
 20. The HVEM polypeptide variant of claim 1, wherein the variant further comprises a dimerizing domain.
 21. The HVEM polypeptide variant of claim 20, wherein the dimerizing domain is an antibody Fc domain. 22.-30. (canceled)
 31. A pharmaceutical composition comprising the HVEM polypeptide variant of claim 1 and a pharmaceutically acceptable carrier.
 32. (canceled)
 33. An isolated nucleic acid molecule encoding the HVEM polypeptide variant of claim
 1. 34.-36. (canceled)
 37. A method for treating an inflammatory disease in a subject comprising administering to the subject a pharmaceutical composition comprising a HVEM polypeptide variant that specifically binds BTLA and does not bind CD160, wherein the administering results in treatment of the inflammatory disease.
 38. The method of claim 37, wherein the inflammatory disease is selected from the group consisting of rheumatoid arthritis, lupus, autoimmune diseases, Crohn's disease, ulcerative colitis, inflammatory bowel diseases, asthma, dermatitis, diverticulitis, pelvic inflammatory disease, atheroscloerosis, allergies, myopathies, cancer, and leukocyte defects.
 39. (canceled)
 40. The method of claim 37, wherein the HVEM polypeptide variant inhibits activation of natural killer (NK) cells.
 41. The method of claim 37, wherein the HVEM polypeptide variant is a negative regulator of IL-2 signaling. 42.-46. (canceled)
 47. A method for inhibiting a proinflammatory response in a subject comprising administering to the subject an agent which inhibits binding of herbesvirus entry mediator (HVEM) to CD160 or agonizing binding of BTLA to HVEM, wherein the administering results in inhibition of the proinflammatory response.
 48. The method of claim 47, wherein the agent inhibits activation of natural killer (NK) cells.
 49. The method of claim 47, wherein the agent is a negative regulator of IL-2 signaling.
 50. The method of claim 47, wherein the agent is a polypeptide.
 51. The method of claim 50, wherein the polypeptide is an antibody, or fragment thereof.
 52. The method of claim 50, wherein the polypeptide specifically inhibits binding of HVEM to CD160 without inhibiting binding of HVEM to BTLA. 